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CVE-2026-27135

nghttp2 Denial of service: Assertion failure due to the missing state validation

Published: Mar 18, 2026Updated: May 13, 2026 Sources: CVE List NVDCWE-617
NVD MITRE
7.5CVSSHIGH
EPSS Score
0.6%
Top 57.9%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

Description

nghttp2 is an implementation of the Hypertext Transfer Protocol version 2 in C. Prior to version 1.68.1, the nghttp2 library stops reading the incoming data when user facing public API `nghttp2_session_terminate_session` or `nghttp2_session_terminate_session2` is called by the application. They might be called internally by the library when it detects the situation that is subject to connection error. Due to the missing internal state validation, the library keeps reading the rest of the data after one of those APIs is called. Then receiving a malformed frame that causes FRAME_SIZE_ERROR causes assertion failure. nghttp2 v1.68.1 adds missing state validation to avoid assertion failure. No known workarounds are available.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:NI:NA:H
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:NIntegrity
None
A:HAvailability
High
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Weaknesses

CWE-617

Affected Products

nghttp2nghttp2
Library
OSS Libraries / generic-library
nghttp2oss-projectOSS Librariesaka nghttp2, ngtcp2

Attack Graph

Products CVE Techniques Tactics

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Exploitability

Official Patch Available

MITRE ATT&CK

1 technique
Impact
View detailed technique mapping

References

https://github.com/nghttp2/nghttp2/security/advisories/GHSA-6933-cjhr-5qg6
github.com
https://github.com/nghttp2/nghttp2/commit/5c7df8fa815ac1004d9ecb9d1f7595c4d37f46e1
github.com
http://www.openwall.com/lists/oss-security/2026/03/20/3
openwall.com
and 1 more references View all →

Timeline

Published
Mar 18, 2026
Last Updated
May 13, 2026

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