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Vulnerabilities

Vulnerability · CVE-2026-115877

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

Published Oct 23, 2026 · catalog updated Oct 24, 2026 · Red Hat Red Hat Enterprise Linux

Last checked Nov 6, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-115877. EPSS is 0.26%. Act only if a listed version of Red Hat Red Hat Enterprise Linux is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
Medium5.4
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.26%
Remediation
Advisory link
Affected products
Debian:12 twisted · Debian:13 twisted · Debian:14 twisted · pypi twisted

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • Debian:12 twisted22.4.0-4, 22.4.0-4+deb12u1, 23.10.0-1
  • Debian:13 twisted24.11.0-1, 25.5.0-1, 25.5.0-2
  • Debian:14 twisted24.11.0-1, 25.5.0-1, 25.5.0-2
  • pypi twistedversion unspecified

How to fix CVE-2026-115877

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-115877. EPSS is 0.26%. Act only if a listed version of Red Hat Red Hat Enterprise Linux is installed.

Which versions are affected?

Compare what you have installed with 22.4.0-4, 22.4.0-4+deb12u1, 23.10.0-1, 24.11.0-1, 25.5.0-1, 25.5.0-2. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-444: HTTP Request Smuggling. EPSS 0.26%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Debian security

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 23, 2026 · Red Hat Security Data

    Detected

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

  2. Oct 24, 2026 · Trivy Vulnerability DB

    Updated

    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

Sources

  • CVE.orgVulnerability recordCVE-2026-115877

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-115877

    30-day exploitation probability 0.26%

    first.org
  • GitLab Advisory DatabasePackage advisoryCVE-2026-115877

    An incomplete header-value validation (CWE-444) in the Twisted HTTP server lets a bare carriage return or line feed in a header value hide a following header from the parser. twisted.web.http.HTTPChannel.headerReceived rejects a NUL byte in a header value but not a bare CR or LF, even though RFC 9110 section 5.5 requires a recipient to reject all three. Because the channel splits requests only on

    advisories.gitlab.com
  • Red Hat Security DataVendor advisoryCVE-2026-115877

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

    access.redhat.com
  • Trivy Vulnerability DBPackage advisoryDEBIAN-CVE-2026-115877

    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 l

    osv.dev

References

Freshness

Last verified in this catalog Nov 6, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • FIRST EPSSNov 6, 2026
  • GitLab Advisory DatabaseOct 27, 2026
  • Red Hat Security DataOct 26, 2026
  • CVE.orgOct 24, 2026
  • Trivy Vulnerability DBOct 24, 2026