SB2026060494 - Remote denial of service in Envoy

Description

This security bulletin contains information about 1 vulnerability.

1) Asymmetric Resource Consumption (Amplification) (CVE-ID: CVE-2026-47774)

CWE-ID: CWE-405 - Asymmetric Resource Consumption (Amplification)

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber

The vulnerability allows a remote attacker to cause a denial of service.

The vulnerability exists due to asymmetric resource consumption in HTTP/2 downstream request processing when handling specially crafted cookie headers with HPACK decoded-size amplification. A remote attacker can send specially crafted HTTP/2 requests to cause a denial of service.

Flow-control stalling can prolong stream lifetime and delay reclamation of per-stream memory, increasing the effectiveness of the attack.

Remediation

Install update from vendor's website.

References

• https://github.com/envoyproxy/envoy/security/advisories/GHSA-22m2-hvr2-xqc8
• https://blog.calif.io/p/codex-discovered-a-hidden-http2-bomb