# CVE-2024-30255: HTTP/2: CPU exhaustion due to CONTINUATION frame flood > Attackers can cause CPU exhaustion and denial of service in Envoy proxy by flooding HTTP/2 CONTINUATION frames, requiring an upgrade to mitigate. - **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 4 Apr 2024 - **Updated:** 4 Nov 2025 - **Also known as:** BIT-envoy-2024-30255, GHSA-j654-3ccm-vfmm ## What is CVE-2024-30255? CVE-2024-30255 is a medium-severity denial of service vulnerability in Envoyproxy Envoy, published on 4 Apr 2024. An attacker can exploit it over the internet without logging in, with no action from the victim. ### Official description Envoy is a cloud-native, open source edge and service proxy. The HTTP/2 protocol stack in Envoy versions prior to 1.29.3, 1.28.2, 1.27.4, and 1.26.8 are vulnerable to CPU exhaustion due to flood of CONTINUATION frames. Envoy's HTTP/2 codec allows the client to send an unlimited number of CONTINUATION frames even after exceeding Envoy's header map limits. This allows an attacker to send a sequence of CONTINUATION frames without the END_HEADERS bit set causing CPU utilization, consuming approximately 1 core per 300Mbit/s of traffic and culminating in denial of service through CPU exhaustion. Users should upgrade to version 1.29.3, 1.28.2, 1.27.4, or 1.26.8 to mitigate the effects of the CONTINUATION flood. As a workaround, disable HTTP/2 protocol for downstream connections. Weakness: CWE-390 (Detection of Error Condition Without Action) ## Which versions are affected by CVE-2024-30255? 1 open source package ship an affected version, including envoy. It affects 1 product. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `envoy` | Bitnami | All versions | 1.26.8, 1.27.4, 1.28.2, 1.29.3 | Products: Envoyproxy Envoy. ## How do I fix CVE-2024-30255? Upgrade envoy to a fixed version for your release line: 1.26.8, 1.27.4, 1.28.2 or 1.29.3. ## Is CVE-2024-30255 being exploited? There is no known exploitation of CVE-2024-30255 in the wild and no public exploit code. Public exploit code: - CVE-2024-30255 This repository contains a proof-of-concept (PoC) Python script to demonstrate the CPU exhaustion vulnerability in Envoy caused by a flood of CONTINUATION frames. (github_poc): https://github.com/blackmagic2023/Envoy-CPU-Exhaustion-Vulnerability-PoC ## 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-2024-30255 and fix it if it is affected. What it is: CVE-2024-30255 is a medium-severity denial of service vulnerability in Envoyproxy Envoy, published on 4 Apr 2024. 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-2024-30255 in the wild and no public exploit code. Affected packages and fixed versions: - envoy (Bitnami): affected all versions; fixed in 1.26.8, 1.27.4, 1.28.2, 1.29.3 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-2024-30255/ (Markdown: https://insights.sbomify.com/CVE-2024-30255/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2024-30255 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-30255 - OSV: https://osv.dev/vulnerability/CVE-2024-30255 --- From sbomify Insights: https://insights.sbomify.com/CVE-2024-30255/ Summaries are generated and may contain mistakes; the official description above is the record.