# 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. - **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 18 Mar 2026 - **Updated:** 15 Oct 2026 - **Also known as:** ALPINE-CVE-2026-27135, ALSA-2026:7666, ALSA-2026:7667, ALSA-2026:7668, AZL-80103, AZL-80219, AZL-80235, BELL-CVE-2026-27135, CLEANSTART-2026-CI31043, CLSA-2026-1777974095, CLSA-2026-1787303674, DEBIAN-CVE-2026-27135, ECHO-0b39-783f-9cd3, GHSA-6933-cjhr-5qg6, JLSEC-2026-5, MGASA-2026-0199, MINI-j53j-532g-vf6q, OESA-2026-1754, RHSA-2026:6190, RHSA-2026:7666, RHSA-2026:7667, RHSA-2026:7668, RHSA-2026:77939, RHSA-2026:8538, RHSA-2026:8539, RHSA-2026:8540, RHSA-2026:8541, RHSA-2026:8545, RHSA-2026:8546, RHSA-2026:8547, RHSA-2026:8548, RHSA-2026:8868, RLSA-2026:7666, RLSA-2026:7667, RLSA-2026:7668, ROOT-OS-ALPINE-315-CVE-2026-27135, ROOT-OS-ALPINE-320-CVE-2026-27135, SUSE-SU-2026:1056-1, SUSE-SU-2026:1074-1, SUSE-SU-2026:1247-1, SUSE-SU-2026:1350-1, SUSE-SU-2026:20833-1, SUSE-SU-2026:20870-1, SUSE-SU-2026:20925-1, SUSE-SU-2026:20950-1, UBUNTU-CVE-2026-27135, USN-8233-1, openSUSE-SU-2026:10437-1, openSUSE-SU-2026:20413-1 ## 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 (Reachable Assertion) ## Which versions are affected by CVE-2026-27135? It affects 1 product. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `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: Nghttp2 Nghttp2. ## How do I fix CVE-2026-27135? Upgrade to a fixed version. ## 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 - [CVE-2026-58055](https://insights.sbomify.com/CVE-2026-58055/): nghttp2 nghttpx - HTTP Request/Response Smuggling via Upgrade Request with Content-Length (medium 6.3) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-27135 and fix it if it is affected. What it is: 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. Exploitation: There is no known exploitation of CVE-2026-27135 in the wild and no public exploit code. Affected product: nghttp2. No package-level version data is available, so check the vendor advisory linked from the reference page. Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2026-27135/ (Markdown: https://insights.sbomify.com/CVE-2026-27135/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-27135 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-27135 - OSV: https://osv.dev/vulnerability/CVE-2026-27135 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-27135/ Summaries are generated and may contain mistakes; the official description above is the record.