CVE-2026-115877

Name	CVE-2026-115877
Description	Twisted is an event-based framework for internet applications, supporting Python 3.6+. Prior to 26.10.0rc1, twisted.web.http.HTTPChannel.headerReceived rejects a NUL byte in an HTTP header value but accepts a bare carriage return or bare line feed. Because Twisted splits header lines only on CRLF, a hidden Content-Length header can remain folded into another value while a lenient front end treats the bare character as a line terminator. The resulting framing disagreement can smuggle a following request past front-end access controls, poison a shared connection or cache, and expose a later client to the wrong response. This issue is an incomplete-fix residual of earlier Twisted request-smuggling protections. This issue is fixed in version 26.10.0rc1.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
Debian Bugs	1151938

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
twisted (PTS)	bookworm, bookworm (security)	22.4.0-4+deb12u1	vulnerable
	trixie	24.11.0-1	vulnerable
	sid, forky	26.4.0-6	vulnerable

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

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
twisted	source	(unstable)	(unfixed)			1151938

Notes

[trixie] - twisted <no-dsa> (Minor issue)
https://github.com/twisted/twisted/security/advisories/GHSA-q7qq-6mhp-9rc4
https://github.com/twisted/twisted/pull/12755
Fixed by: https://github.com/twisted/twisted/commit/022b6f7feb5980166c71f54e2c0d8f4f21ff6e1a (twisted-26.10.0rc1)
Fixed by: https://github.com/twisted/twisted/commit/1616f702d36eda8990a5a5b22ad70fab140a7eb1 (twisted-26.10.0rc1)