CVE-2026-84380

NameCVE-2026-84380
DescriptionHTTPX2 is a next generation HTTP client for Python. Prior to 2.11.0, Request._prepare() in src/httpx2/httpx2/_models.py can add a body-derived Content-Length header to a request that already contains a caller-supplied Transfer-Encoding header because its setdefault() processing checks each default header independently rather than treating the two framing headers as mutually exclusive. Fixed-size byte, JSON, form, and known-length multipart bodies can therefore be serialized over HTTP/1.1 with both headers, allowing request smuggling or connection desynchronization when downstream intermediaries disagree about which framing header takes precedence. This issue is fixed in version 2.11.0.
SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
python-httpx2 (PTS)forky2.5.0-1vulnerable
sid2.12.0-1fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
python-httpx2source(unstable)2.12.0-1

Notes

https://github.com/pydantic/httpx2/security/advisories/GHSA-pf96-p4fj-6566
https://github.com/pydantic/httpx2/pull/1137
Fixed by: https://github.com/pydantic/httpx2/commit/829b93a2393212996f613e635261f777d9ec6eab (v2.11.0)

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