CVE-2024-30255
A public proof of concept exists; no exploitation attested.
- Published2024-04-04
- Fixed in1.29.3 · 1.28.2 · 1.27.4 · 1.26.8
- WeaknessCWE-390
Am I affected?
Debian, Ubuntu or Red Hat sometimes backport a fix without changing the upstream version number: such a version reads « to verify », never « affected ».With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.
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.
Timeline
dates in UTC- 2024-04-0420:15CVE publishedNVD
- 2026-10-2319:23First public proof of conceptPoC-in-GitHub
- 2026-10-2319:23EPSS crossed 10 %FIRST EPSS
Observed activity
isMalicious corpus · updated 2026-10-23 18:48 UTCBlock these indicators
- Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2024-30255?format=txt
- CSV export: https://api.ismalicious.com/edl/cve/CVE-2024-30255?format=csv
- TAXII collection of exploited CVEs
- The EDL and CSV take an API key on the Pro plan.
Versions per branch
NVD · CISA-ADP| Branch | Affected | Fixed in | Source |
|---|---|---|---|
| 1.29 | ≥ 1.29.0, < 1.29.3 | 1.29.3 | NVD · CISA-ADP |
| 1.28 | ≥ 1.28.0, < 1.28.2 | 1.28.2 | NVD · CISA-ADP |
| 1.27 | ≥ 1.27.0, < 1.27.4 | 1.27.4 | NVD · CISA-ADP |
| 1.26 | < 1.26.8 | 1.26.8 | NVD · CISA-ADP |
as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.
Distribution builds and vendor advisories
Packages from OSV.dev and products from the vendors' CSAF advisories.
version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.
Vendor advisories
Red Hat Bug Fix Advisory: Updated 7.1 container image is now available in the Red Hat Ecosystem Catalog
Fix
- Update Envoy to 1.29.3 · 1.28.2 · 1.27.4 · 1.26.8
- Vendor fix Red Hat Product Security RHBA-2025:1772 · 20 productsBefore applying this update, make sure all previously released errata relevant to your system have been applied. For details on how to apply this update, refer to: https://access.redhat.com/articles/2789521 For supported configurations, refer to: https://access.redhat.com/articles/1548993
- Workaround from the vendor Red Hat Product Security RHBA-2025:1772 · 20 productsRed Hat has investigated whether a possible mitigation exists for this issue, and has not been able to identify a practical example. Please update the affected package as soon as possible.
Advisories and patches
- github.comPatch
Detection
read 2026-10-23 19:24 UTC- Nuclei template
- none so far ProjectDiscovery
- Exploit-DB
- no entry Exploit-DB
- Proof-of-concept repositories
- 1 repository, unverifiedblackmagic2023/Envoy-CPU-Exhaustion-Vulnerability-PoC PoC-in-GitHub
Sources
- CISA-ADPSSVC decisionnone2024-04-08
- OpenCVESSVC decisionnone—
- CNACVSS 3.15.3read 2026-10-23
- NVDCVSS 3.17.5read 2026-10-23
- CNAweakness (CWE)CWE-390read 2026-10-23
- FIRST EPSSEPSS score87.8 %read 2026-10-23
- PoC-in-GitHubproof of concept1read 2026-10-23
Technical details
- CVSS v3 Vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Published
- 2024-04-04
- Last Modified
- 2026-06-17
- NVD status
- Modified
Frequently asked questions
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