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.
Metrics
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HWeakness enumeration
Affected software
| Vendor | Product | Versions |
|---|---|---|
| envoyproxy | envoy | >= 1.29.0, < 1.29.3; >= 1.28.0, < 1.28.2; >= 1.27.0, < 1.27.4; < 1.26.8 |
| envoyproxy | envoy | >= 1.29.0, < 1.29.3; >= 1.28.0, < 1.28.2; >= 1.27.0, < 1.27.4; < 1.26.8 |
References
- http://www.openwall.com/lists/oss-security/2024/04/03/16Mailing List, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2024/04/05/3Mailing List
- https://github.com/envoyproxy/envoy/security/advisories/GHSA-j654-3ccm-vfmmPatch, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2024/04/03/16Mailing List, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2024/04/05/3Mailing List
- https://github.com/envoyproxy/envoy/security/advisories/GHSA-j654-3ccm-vfmmPatch, Third Party Advisory
- https://www.kb.cert.org/vuls/id/421644
Timeline
- Published
- Apr 4, 2024
- Last modified
- Jun 17, 2026
- NVD status
- Modified