Memory leak in envoy - CVE-2026-73550
Published: August 26, 2026
Vulnerability identifier: #VU145870
CSH Severity: Medium
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-2026-73550
CWE-ID: CWE-401
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 missing release of memory after effective lifetime in Envoy HTTP/2 header handling when processing HTTP/2 requests containing repeated discarded host headers while :authority is present. A remote attacker can send a specially crafted HTTP/2 request to cause a denial of service.
Exploitation requires the runtime guard for HTTP/2 discarded host header behavior to be enabled and relies on ordinary host headers being discarded before request header byte and count limits are charged.
Affected software
envoy
Istio
Istio
How to mitigate CVE-2026-73550
Install security update from vendor's website.
envoy - addressed in versions 1.36.10, 1.37.6, 1.38.4, 1.39.1
Istio - addressed in versions 1.29.7, 1.30.4
Istio - addressed in versions 1.29.7, 1.30.4