Publish GHSA-rfg2-pjw2-56x2

Author: advisory-database[bot]

advisories/github-reviewed/2026/05/GHSA-rfg2-pjw2-56x2/GHSA-rfg2-pjw2-56x2.json

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+{
+  "schema_version": "1.4.0",
+  "id": "GHSA-rfg2-pjw2-56x2",
+  "modified": "2026-05-29T20:18:53Z",
+  "published": "2026-05-29T20:18:53Z",
+  "aliases": [
+    "CVE-2026-47184"
+  ],
+  "summary": "zeroconf has unbounded DNS record cache that allows LAN-local memory exhaustion via multicast flood",
+  "details": "### Impact\n\n`DNSCache._async_add` inserted every response record into `cache`, `_expirations`, `_expire_heap`, and `service_cache` with no cap on entry count. The only pre-existing protection was a PTR TTL floor (`_DNS_PTR_MIN_TTL = 1125` s, RFC 6762 §10), which actually *prolonged* attacker-injected records, and a periodic `async_expire` on `_CACHE_CLEANUP_INTERVAL = 10` s that could not keep up with a flood.\n\nAny unauthenticated host on the local link (UDP/5353, `224.0.0.251` / `ff02::fb`) can multicast valid mDNS responses with unique names (RFC 6762 §11 allows up to 253 bytes each) and watch them accumulate. On memory-constrained deployments (Home Assistant on Raspberry-Pi-class hardware is the canonical victim) sustained traffic OOM-kills the process; under lighter load, every cache lookup and every periodic expiry pass grows linearly slower, starving asyncio and breaking unrelated zeroconf consumers (discovery, registration, ServiceBrowser callbacks). A second variant — re-multicasting cached records with shifting TTLs — grows `_expire_heap` unbounded between cleanup runs without touching `cache` or `_total_records`.\n\n### Patches\n\nFixed in `zeroconf` 0.149.6 ([PR #1718](https://github.com/python-zeroconf/python-zeroconf/pull/1718)). Upgrade to `>= 0.149.6`.\n\n### Workarounds\n\nThere is no in-process workaround; upgrading is the fix. Otherwise, restrict mDNS (UDP/5353) to trusted Layer-2 segments via AP client isolation, guest-network separation, or host firewall rules.\n\n### Resources\n\n- [PR #1718](https://github.com/python-zeroconf/python-zeroconf/pull/1718), fix\n- [Issue #1715](https://github.com/python-zeroconf/python-zeroconf/issues/1715), public tracking issue\n- [RFC 6762 §10](https://www.rfc-editor.org/rfc/rfc6762#section-10), [RFC 6762 §11](https://www.rfc-editor.org/rfc/rfc6762#section-11), [CWE-400](https://cwe.mitre.org/data/definitions/400.html)",
+  "severity": [
+    {
+      "type": "CVSS_V3",
+      "score": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
+    }
+  ],
+  "affected": [
+    {
+      "package": {
+        "ecosystem": "PyPI",
+        "name": "zeroconf"
+      },
+      "ranges": [
+        {
+          "type": "ECOSYSTEM",
+          "events": [
+            {
+              "introduced": "0"
+            },
+            {
+              "fixed": "0.149.7"
+            }
+          ]
+        }
+      ]
+    }
+  ],
+  "references": [
+    {
+      "type": "WEB",
+      "url": "https://github.com/python-zeroconf/python-zeroconf/security/advisories/GHSA-rfg2-pjw2-56x2"
+    },
+    {
+      "type": "WEB",
+      "url": "https://github.com/python-zeroconf/python-zeroconf/issues/1715"
+    },
+    {
+      "type": "WEB",
+      "url": "https://github.com/python-zeroconf/python-zeroconf/pull/1718"
+    },
+    {
+      "type": "PACKAGE",
+      "url": "https://github.com/python-zeroconf/python-zeroconf"
+    }
+  ],
+  "database_specific": {
+    "cwe_ids": [
+      "CWE-400",
+      "CWE-770"
+    ],
+    "severity": "MODERATE",
+    "github_reviewed": true,
+    "github_reviewed_at": "2026-05-29T20:18:53Z",
+    "nvd_published_at": null
+  }
+}