Input validation error in nghttp2 - CVE-2026-27135
Published: April 23, 2026
Vulnerability identifier: #VU127046
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-27135
CWE-ID: CWE-20
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: nghttp2
Affected software:
nghttp2
nghttp2
Detailed vulnerability description
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to missing state validation in the nghttp2 session handling logic when processing malformed frames after session termination has been initiated. A remote attacker can send specially crafted frames to cause a denial of service.
For PRIORITY_UPDATE and ALTSVC frames, the affected extension types must be explicitly enabled. Builds with assertions disabled may not crash under the same conditions.
How to mitigate CVE-2026-27135
Install security update from vendor's website.