Asymmetric Resource Consumption (Amplification) in envoy - CVE-2026-47774
Published: June 4, 2026
Vulnerability identifier: #VU133363
CSH Severity: High
CVSS v4: 8.7 [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]
CVE-ID: CVE-2026-47774
CWE-ID: CWE-405
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
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.
Affected software
envoy
App & API Protector Hybrid
App & API Protector Hybrid
How to mitigate CVE-2026-47774
Install security update from vendor's website.
envoy - addressed in versions 1.35.11, 1.36.7, 1.37.3, 1.38.1
App & API Protector Hybrid - update to 1.6.1
App & API Protector Hybrid - update to 1.6.1