CVE-2026-27135

HIGH

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 v3.1 Score

7.5
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Published: 3/18/2026Modified: 7/15/2026

Related Intelligence (1)

CRITICALAi

Siemens SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP

<p><a href="https://github.com/cisagov/CSAF/blob/develop/csaf_files/OT/white/2026/icsa-26-209-04.json"><strong>View CSAF</strong></a></p> <h2>Summary</h2> <p><strong>Multiple vulnerabilities have been identified in the additional GNU/Linux subsystem of the firmware version V3.1.6 for the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP (incl. SIPLUS variant). Siemens is preparing fix versions and recommend

CVE-2021-41617CVE-2023-28531
CISA Advisories

References (55)

https://github.com/nghttp2/nghttp2/commit/5c7df8fa815ac1004d9ecb9d1f7595c4d37f46e1Patchhttps://github.com/nghttp2/nghttp2/security/advisories/GHSA-6933-cjhr-5qg6PatchVendor Advisoryhttp://www.openwall.com/lists/oss-security/2026/03/20/3Mailing ListThird Party Advisoryhttps://lists.debian.org/debian-lts-announce/2026/05/msg00025.htmlhttps://access.redhat.com/errata/RHSA-2026:10065https://access.redhat.com/errata/RHSA-2026:11768https://access.redhat.com/errata/RHSA-2026:13812https://access.redhat.com/errata/RHSA-2026:14773https://access.redhat.com/errata/RHSA-2026:14937https://access.redhat.com/errata/RHSA-2026:15087https://access.redhat.com/errata/RHSA-2026:16008https://access.redhat.com/errata/RHSA-2026:16009https://access.redhat.com/errata/RHSA-2026:16030https://access.redhat.com/errata/RHSA-2026:16174https://access.redhat.com/errata/RHSA-2026:17596https://access.redhat.com/errata/RHSA-2026:19724https://access.redhat.com/errata/RHSA-2026:19725https://access.redhat.com/errata/RHSA-2026:20040https://access.redhat.com/errata/RHSA-2026:20087https://access.redhat.com/errata/RHSA-2026:21656https://access.redhat.com/errata/RHSA-2026:21690https://access.redhat.com/errata/RHSA-2026:21695https://access.redhat.com/errata/RHSA-2026:25096https://access.redhat.com/errata/RHSA-2026:27200https://access.redhat.com/errata/RHSA-2026:27201https://access.redhat.com/errata/RHSA-2026:6190https://access.redhat.com/errata/RHSA-2026:7080https://access.redhat.com/errata/RHSA-2026:7123https://access.redhat.com/errata/RHSA-2026:7302https://access.redhat.com/errata/RHSA-2026:7310https://access.redhat.com/errata/RHSA-2026:7350https://access.redhat.com/errata/RHSA-2026:7666https://access.redhat.com/errata/RHSA-2026:7667https://access.redhat.com/errata/RHSA-2026:7668https://access.redhat.com/errata/RHSA-2026:7670https://access.redhat.com/errata/RHSA-2026:7675https://access.redhat.com/errata/RHSA-2026:7896https://access.redhat.com/errata/RHSA-2026:7983https://access.redhat.com/errata/RHSA-2026:8339https://access.redhat.com/errata/RHSA-2026:8538https://access.redhat.com/errata/RHSA-2026:8539https://access.redhat.com/errata/RHSA-2026:8540https://access.redhat.com/errata/RHSA-2026:8541https://access.redhat.com/errata/RHSA-2026:8545https://access.redhat.com/errata/RHSA-2026:8546https://access.redhat.com/errata/RHSA-2026:8547https://access.redhat.com/errata/RHSA-2026:8548https://access.redhat.com/errata/RHSA-2026:8868https://access.redhat.com/errata/RHSA-2026:9711https://access.redhat.com/errata/RHSA-2026:9832https://access.redhat.com/errata/RHSA-2026:9874https://access.redhat.com/security/cve/CVE-2026-27135https://bugzilla.redhat.com/show_bug.cgi?id=2448754https://cert-portal.siemens.com/productcert/html/ssa-019113.htmlhttps://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-27135.json