fix: v3.15.3 hotfix — python-multipart CVE + recover from broken v3.15.2 tag#23
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…5.2 tag Two issues bundled into one hotfix release. 1. python-multipart 0.0.26 → 0.0.27: patches a DoS vulnerability in MultipartParser header parsing (unbounded part headers cause CPU exhaustion). Affects every ASGI app in the FastMCP dep chain. The dependabot PR (#21) flagged this; closing it was wrong on my part. 2. v3.15.2 was tagged at 308ed41 (pre-PR-#22 merge) instead of 6b19ec4 because a stale uv.lock blocked the local fast-forward during release scripting. The broken v3.15.2 tag stays as a graveyard. v3.15.3 is the canonical version with both the MCP startup robustness work (PR #22 contents) AND this security bump.
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Why a hotfix
Two issues converged.
1. CVE: python-multipart DoS via unbounded part headers
python-multipart0.0.26 (transitive via fastmcp) has a denial-of-service vulnerability inMultipartParserheader parsing. An attacker can send oversized individual header values OR many repeated headers without terminating the header block; both cause CPU exhaustion before request rejection. Affects every ASGI / Starlette / FastAPI app in the dep chain.Patched in 0.0.27 by enforcing default parser limits for max header count and header size.
Dependabot opened PR #21 with this bump. I closed it earlier today thinking it was a routine patch bump — that was the wrong call given it carries a CVE fix. This hotfix re-applies the bump on a current branch.
2. v3.15.2 release was tagged at the wrong commit
PR #22 merged on GitHub at
6b19ec4(with pyproject correctly bumped to 3.15.2 and the v3.15.2 CHANGELOG section). My local main was stuck at308ed41due to a stale uv.lock blocking the fast-forward, so when I rangit tag -a v3.15.2 && git push, the tag landed at308ed41(where pyproject still says 3.15.1, no v3.15.2 CHANGELOG, GitHub release notes empty).The broken v3.15.2 tag stays as a graveyard entry (force-push of a tag that's been live ~10 minutes is destructive; not worth the rewrite). v3.15.3 is the canonical version that bundles BOTH PR #22's contents AND this security fix.
What lands here
uv.lock: python-multipart 0.0.26 → 0.0.27pyproject.toml: 3.15.2 → 3.15.3.claude-plugin/marketplace.json: 3.15.2 → 3.15.3CHANGELOG.md: new v3.15.3 section explaining both issues; v3.15.2 section preserved for history52 targeted tests still pass locally.
Upgrade path
If you're on v3.15.0, v3.15.1, or v3.15.2 — upgrade directly to v3.15.3. Skip v3.15.2 (broken tag).
Process lessons
git tagfrom a working tree that hasn't successfullygit pull'd the merge commit. The release scripting now needs a guard.