Skip to content
Fencer Intel
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 17d ago modified 11d ago also EUVD-2026-109153 , GHSA-q7qq-6mhp-9rc4

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
  • twistedmatrix 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

Is CVE-2026-115877 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

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
11d ago

Exploit prediction

0.26% chance of exploitation in the next 30 days, higher than 17% of all scored CVEs (FIRST EPSS, 2026-11-09).

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 Intel 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.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.