Input validation error in envoy - CVE-2026-73552
Published: August 26, 2026
Vulnerability identifier: #VU145864
CSH Severity: Medium
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-73552
CWE-ID: CWE-20
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to disclose sensitive information.
The vulnerability exists due to improper input validation in the HTTP RBAC safe_regex header matcher when processing RFC-valid obs-text header values containing invalid UTF-8 bytes. A remote attacker can send a specially crafted request header to disclose sensitive information.
Exploitation requires an HTTP RBAC policy that applies safe_regex with negative logic and a protected operation that remains reachable when another consumer still observes the preserved header bytes.
Affected software
envoy
Istio
Istio
How to mitigate CVE-2026-73552
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