CVE-2026-27135 nghttp2 Denial of service: Assertion failure due to the missing state validation
Attackers can cause a denial of service in applications using nghttp2 by triggering an assertion failure via malformed frames after session termination.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-27135?
CVE-2026-27135 is a high-severity denial of service vulnerability in nghttp2, published on 18 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-617
Which versions are affected by CVE-2026-27135?
It affects 1 product.
Linux distribution packages (40)
libnghttp2 AlmaLinux:10 | All versions | 1.64.0-2.el10_1.1 |
libnghttp2-devel AlmaLinux:10 | All versions | 1.64.0-2.el10_1.1 |
nghttp2 AlmaLinux:10 | All versions | 1.64.0-2.el10_1.1 |
libnghttp2 AlmaLinux:8 | All versions | 1.33.0-6.el8_10.2 |
libnghttp2-devel AlmaLinux:8 | All versions | 1.33.0-6.el8_10.2 |
nghttp2 AlmaLinux:8 | All versions | 1.33.0-6.el8_10.2 |
libnghttp2 AlmaLinux:9 | All versions | 1.43.0-6.el9_7.1 |
libnghttp2-devel AlmaLinux:9 | All versions | 1.43.0-6.el9_7.1 |
nghttp2 AlmaLinux:9 | All versions | 1.43.0-6.el9_7.1 |
libnghttp2 Red Hat:enterprise_linux:10.1 | All versions | 0:1.64.0-2.el10_1.1 |
libnghttp2-debuginfo Red Hat:enterprise_linux:10.1 | All versions | 0:1.64.0-2.el10_1.1 |
libnghttp2-devel Red Hat:enterprise_linux:10.1 | All versions | 0:1.64.0-2.el10_1.1 |
nghttp2 Red Hat:enterprise_linux:10.1 | All versions | 0:1.64.0-2.el10_1.1 |
nghttp2-debuginfo Red Hat:enterprise_linux:10.1 | All versions | 0:1.64.0-2.el10_1.1 |
nghttp2-debugsource Red Hat:enterprise_linux:10.1 | All versions | 0:1.64.0-2.el10_1.1 |
libnghttp2 Red Hat:enterprise_linux:8::baseos | All versions | 0:1.33.0-6.el8_10.2 |
libnghttp2-debuginfo Red Hat:enterprise_linux:8::baseos | All versions | 0:1.33.0-6.el8_10.2 |
nghttp2 Red Hat:enterprise_linux:8::baseos | All versions | 0:1.33.0-6.el8_10.2 |
nghttp2-debuginfo Red Hat:enterprise_linux:8::baseos | All versions | 0:1.33.0-6.el8_10.2 |
nghttp2-debugsource Red Hat:enterprise_linux:8::baseos | All versions | 0:1.33.0-6.el8_10.2 |
libnghttp2-debuginfo Red Hat:enterprise_linux:8::crb | All versions | 0:1.33.0-6.el8_10.2 |
libnghttp2-devel Red Hat:enterprise_linux:8::crb | All versions | 0:1.33.0-6.el8_10.2 |
nghttp2 Red Hat:enterprise_linux:8::crb | All versions | 0:1.33.0-6.el8_10.2 |
nghttp2-debuginfo Red Hat:enterprise_linux:8::crb | All versions | 0:1.33.0-6.el8_10.2 |
nghttp2-debugsource Red Hat:enterprise_linux:8::crb | All versions | 0:1.33.0-6.el8_10.2 |
libnghttp2 Red Hat:enterprise_linux:9::baseos | All versions | 0:1.43.0-6.el9_7.1 |
libnghttp2-debuginfo Red Hat:enterprise_linux:9::baseos | All versions | 0:1.43.0-6.el9_7.1 |
nghttp2 Red Hat:enterprise_linux:9::baseos | All versions | 0:1.43.0-6.el9_7.1 |
nghttp2-debuginfo Red Hat:enterprise_linux:9::baseos | All versions | 0:1.43.0-6.el9_7.1 |
nghttp2-debugsource Red Hat:enterprise_linux:9::baseos | All versions | 0:1.43.0-6.el9_7.1 |
libnghttp2-debuginfo Red Hat:enterprise_linux:9::crb | All versions | 0:1.43.0-6.el9_7.1 |
libnghttp2-devel Red Hat:enterprise_linux:9::crb | All versions | 0:1.43.0-6.el9_7.1 |
nghttp2 Red Hat:enterprise_linux:9::crb | All versions | 0:1.43.0-6.el9_7.1 |
nghttp2-debuginfo Red Hat:enterprise_linux:9::crb | All versions | 0:1.43.0-6.el9_7.1 |
nghttp2-debugsource Red Hat:enterprise_linux:9::crb | All versions | 0:1.43.0-6.el9_7.1 |
libnghttp2 Red Hat:enterprise_linux_eus:10.0 | All versions | 0:1.64.0-2.el10_0.1 |
libnghttp2-debuginfo Red Hat:enterprise_linux_eus:10.0 | All versions | 0:1.64.0-2.el10_0.1 |
libnghttp2-devel Red Hat:enterprise_linux_eus:10.0 | All versions | 0:1.64.0-2.el10_0.1 |
nghttp2 Red Hat:enterprise_linux_eus:10.0 | All versions | 0:1.64.0-2.el10_0.1 |
nghttp2-debuginfo Red Hat:enterprise_linux_eus:10.0 | All versions | 0:1.64.0-2.el10_0.1 |
Products include Nghttp2 Nghttp2.
How do I fix CVE-2026-27135?
Upgrade to a fixed version.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-27135 being exploited?
There is no known exploitation of CVE-2026-27135 in the wild and no public exploit code.
Other vulnerabilities in nghttp2
Sources
Also known as ALPINE-CVE-2026-27135, ALSA-2026:7666, ALSA-2026:7667, ALSA-2026:7668, AZL-80103, AZL-80219 and 43 more.