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Fencer Vulns
medium 5.4

CVE-2026-115877 json

Twisted: HTTP Request Smuggling in twisted.web via a Bare CR or LF in a Header Value

published 2026-10-23 16 d ago modified 2026-10-29 10 d ago also GHSA-q7qq-6mhp-9rc4 , EUVD-2026-109153

cvss
5.4
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 17%
public exploits
0
none known

Summary

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.

Patch / fix

  • pypi twisted 26.10.0rc1
  • twisted Debian 14 26.10.0-1

debian advisories DEBIAN-CVE-2026-115877

  • python-Twisted openSUSE Tumbleweed 26.10.0-1.1

opensuse advisories openSUSE-SU-2026:12381-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-115877 updated cvss 5.4

twisted: Twisted: HTTP request smuggling via improper header delimiter handling

  • Red Hat Ansible Automation Platform 2 python-twisted 23.10.0-1.el9ap, python3x-twisted 23.10.0-1.el8ap, python3.11-twisted 24.7.0-1.el9ap, python3.12-twisted 24.7.0-2.el9ap, automation-controller 4.7.18-1.el9ap, ansible-automation-platform-24/controller-rhel8, +8 more
    affected: workaround, no fix available, no fix planned “Upgrade to twisted 26.10.0rc1 or later; avoid deploying Twisted services behind front-end proxies that accept bare CR/LF as header-value line terminators.”
  • Red Hat OpenStack Platform 16.2 python3-twisted, python-twisted 23.10.0-1.el9ap
    affected: workaround, no fix planned “Upgrade to twisted 26.10.0rc1 or later; avoid deploying Twisted services behind front-end proxies that accept bare CR/LF as header-value line terminators.”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
10 d ago

Exploit prediction

0.26% chance of exploitation in the next 30 days, higher than 17% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/twisted/twisted/security/advisories/GHSA-q7qq-6mhp-9rc4 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 5.4 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N
GitHub 3.1 5.4 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N

Affected packages

ecosystem package affected fixed in
pypi twisted
<26.10.0rc1
26.10.0rc1

Affected products

  • twisted twisted

Classification

Weakness
  • CWE-444 Inconsistent Interpretation of HTTP Requests

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.