Bug 2560182 (CVE-2026-115877)

Summary: CVE-2026-115877 twisted: Twisted: HTTP request smuggling via improper header delimiter handling
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: dschmidt, eglynn, jjoyce, jlanda, jpretori, jschluet, jwong, kshier, lhh, mburns, mgarciac, omaciel, rbobbitt, simaishi, stcannon, yguenane
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in Twisted. The HTTP server component improperly accepts bare carriage return or line feed characters within header values instead of enforcing strict line endings. A remote attacker can exploit this framing disagreement against an upstream proxy to conduct HTTP request smuggling. This flaw can allow attackers to bypass front-end access controls, poison shared connections or web caches, and expose sensitive responses meant for other clients.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Description OSIDB Bzimport 2026-10-23 20:41:21 UTC 
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.