Improper Check for Unusual or Exceptional Conditions in envoy - CVE-2026-73549
Published: August 26, 2026
Vulnerability identifier: #VU145872
CSH Severity: Low
CVSS v4: 6 [CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-73549
CWE-ID: CWE-754
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to cause a denial of service.
The vulnerability exists due to improper check for unusual or exceptional conditions in Utility::copyInternetAddressAndPort() when processing kernel-provided scoped IPv6 destination addresses in ORIGINAL_DST clusters. A remote user can trigger processing of a scoped IPv6 link-local address with a scope ID to cause a denial of service.
This issue is reachable in transparent proxy deployments handling IPv6 link-local traffic, and the crash path requires a real kernel-provided original destination rather than the HTTP header override path.
Affected software
envoy
Istio
Istio
How to mitigate CVE-2026-73549
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