Vulnerability in Twisted
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 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.
Vulnerability class: HTTP Request Smuggling
Published .
CVSS v3 metric
CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
- Twisted — versions < 26.10.0rc1
Weakness classification (CWE)
References
- github.com/twisted/twisted/security/advisories/GHSA-q7qq-6mhp-9rc4
- github.com/twisted/twisted/pull/12755
- github.com/twisted/twisted/commit/022b6f7feb5980166c71f54e2c0d8f4f21ff6e1a
- github.com/twisted/twisted/commit/1616f702d36eda8990a5a5b22ad70fab140a7eb1
- github.com/twisted/twisted/releases/tag/twisted-26.10.0rc1
Frequently asked questions
- What is CVE-2026-115877?
- CVE-2026-115877 is a medium-severity vulnerability in Twisted, classified under Inconsistent Interpretation of HTTP Requests (HTTP Request/Response Smuggling). CVSS score: 5.4/10. Published 2026-10-23.
- How severe is CVE-2026-115877?
- Medium severity. CVSS v3 base score is 5.4 out of 10.