# CVE-2023-35945: Envoy vulnerable to HTTP/2 memory leak in nghttp2 codec > Attackers can cause memory exhaustion and denial of service in Envoy by sending specific HTTP/2 frames, requiring an upgrade to patched versions. - **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:** 13 Jul 2023 - **Updated:** 14 Oct 2026 - **Also known as:** ALPINE-CVE-2023-35945, AZL-27650, AZL-27667, AZL-27682, AZL-27683, BIT-envoy-2023-35945, CLSA-2026-1777947331, CLSA-2026-1778148827, GHSA-jfxv-29pc-x22r, JLSEC-2026-2, OESA-2023-1506, SUSE-SU-2023:3842-1, SUSE-SU-2023:3997-1, SUSE-SU-2023:4102-1, openSUSE-SU-2024:13062-1 ## What is CVE-2023-35945? CVE-2023-35945 is a high-severity denial of service vulnerability in Envoyproxy Envoy, published on 13 Jul 2023. An attacker can exploit it over the internet without logging in, with no action from the victim. ### Official description Envoy is a cloud-native high-performance edge/middle/service proxy. Envoy’s HTTP/2 codec may leak a header map and bookkeeping structures upon receiving `RST_STREAM` immediately followed by the `GOAWAY` frames from an upstream server. In nghttp2, cleanup of pending requests due to receipt of the `GOAWAY` frame skips de-allocation of the bookkeeping structure and pending compressed header. The error return [code path] is taken if connection is already marked for not sending more requests due to `GOAWAY` frame. The clean-up code is right after the return statement, causing memory leak. Denial of service through memory exhaustion. This vulnerability was patched in versions(s) 1.26.3, 1.25.8, 1.24.9, 1.23.11. Weakness: CWE-459 (Incomplete Cleanup), CWE-400 (Uncontrolled Resource Consumption) ## Which versions are affected by CVE-2023-35945? 1 open source package ship an affected version, including envoy. It affects 2 products. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `envoy` | Bitnami | All versions | 1.23.11, 1.24.9, 1.25.8, 1.26.3 | | `nghttp2` | SUSE:Enterprise Storage 7.1 | All versions | 1.40.0-150200.9.1 | | `nghttp2` | SUSE:Linux Enterprise High Performance Computing 15 SP1-LTSS | All versions | 1.40.0-150000.3.14.1 | | `nghttp2` | SUSE:Linux Enterprise High Performance Computing 15 SP2-LTSS | All versions | 1.40.0-150200.9.1 | | `nghttp2` | SUSE:Linux Enterprise High Performance Computing 15 SP3-ESPOS | All versions | 1.40.0-150200.9.1 | | `nghttp2` | SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSS | All versions | 1.40.0-150200.9.1 | | `nghttp2` | SUSE:Linux Enterprise Micro 5.1 | All versions | 1.40.0-150200.9.1 | | `nghttp2` | SUSE:Linux Enterprise Micro 5.2 | All versions | 1.40.0-150200.9.1 | | `nghttp2` | SUSE:Linux Enterprise Micro 5.3 | All versions | 1.40.0-150200.9.1 | | `nghttp2` | SUSE:Linux Enterprise Micro 5.4 | All versions | 1.40.0-150200.9.1 | | `nghttp2` | SUSE:Linux Enterprise Micro 5.5 | All versions | 1.40.0-150200.9.1 | | `nghttp2` | SUSE:Linux Enterprise Module for Basesystem 15 SP4 | All versions | 1.40.0-150200.9.1 | | `nghttp2` | SUSE:Linux Enterprise Module for Basesystem 15 SP5 | All versions | 1.40.0-150200.9.1 | | `nghttp2` | SUSE:Linux Enterprise Server 12 SP5 | All versions | 1.39.2-3.10.1 | | `nghttp2` | SUSE:Linux Enterprise Server 15 SP1-LTSS | All versions | 1.40.0-150000.3.14.1 | | `nghttp2` | SUSE:Linux Enterprise Server 15 SP2-LTSS | All versions | 1.40.0-150200.9.1 | | `nghttp2` | SUSE:Linux Enterprise Server 15 SP3-LTSS | All versions | 1.40.0-150200.9.1 | | `nghttp2` | SUSE:Linux Enterprise Server for SAP Applications 12 SP5 | All versions | 1.39.2-3.10.1 | | `nghttp2` | SUSE:Linux Enterprise Server for SAP Applications 15 SP1 | All versions | 1.40.0-150000.3.14.1 | | `nghttp2` | SUSE:Linux Enterprise Server for SAP Applications 15 SP2 | All versions | 1.40.0-150200.9.1 | | `nghttp2` | SUSE:Linux Enterprise Server for SAP Applications 15 SP3 | All versions | 1.40.0-150200.9.1 | | `nghttp2` | SUSE:Linux Enterprise Software Development Kit 12 SP5 | All versions | 1.39.2-3.10.1 | | `nghttp2` | SUSE:Manager Proxy 4.2 | All versions | 1.40.0-150200.9.1 | | `nghttp2` | SUSE:Manager Server 4.2 | All versions | 1.40.0-150200.9.1 | | `nghttp2` | openSUSE:Leap 15.4 | All versions | 1.40.0-150200.9.1 | | `nghttp2-python` | openSUSE:Leap 15.4 | All versions | 1.40.0-150200.9.1 | | `nghttp2` | openSUSE:Leap 15.5 | All versions | 1.40.0-150200.9.1 | | `nghttp2-python` | openSUSE:Leap 15.5 | All versions | 1.40.0-150200.9.1 | | `nghttp2` | openSUSE:Tumbleweed | All versions | 1.55.1-1.1 | Products: Envoyproxy Envoy, Nghttp2 Nghttp2. ## How do I fix CVE-2023-35945? Upgrade envoy to a fixed version for your release line: 1.23.11, 1.24.9, 1.25.8 or 1.26.3. ## Is CVE-2023-35945 being exploited? It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-35945 exists. ## Other vulnerabilities in Envoyproxy Envoy - [CVE-2022-29226](https://insights.sbomify.com/CVE-2022-29226/): Trivial authentication bypass in Envoy (critical 10.0) - [CVE-2019-18801](https://insights.sbomify.com/CVE-2019-18801/): Memory corruption in n/a (critical 9.8) - [CVE-2019-18802](https://insights.sbomify.com/CVE-2019-18802/): Security feature bypass in n/a (critical 9.8) - [CVE-2020-35470](https://insights.sbomify.com/CVE-2020-35470/): Information disclosure in n/a (high 8.8) - [CVE-2024-23324](https://insights.sbomify.com/CVE-2024-23324/): Envoy ext auth can be bypassed when Proxy protocol filter sets invalid UTF-8 metadata (high 8.6) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2023-35945 and fix it if it is affected. What it is: CVE-2023-35945 is a high-severity denial of service vulnerability in Envoyproxy Envoy, published on 13 Jul 2023. An attacker can exploit it over the internet without logging in, with no action from the victim. Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-35945 exists. Affected packages and fixed versions: - envoy (Bitnami): affected all versions; fixed in 1.23.11, 1.24.9, 1.25.8, 1.26.3 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-2023-35945/ (Markdown: https://insights.sbomify.com/CVE-2023-35945/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2023-35945 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-35945 - OSV: https://osv.dev/vulnerability/CVE-2023-35945 --- From sbomify Insights: https://insights.sbomify.com/CVE-2023-35945/ Summaries are generated and may contain mistakes; the official description above is the record.