NULL pointer dereference in envoy - CVE-2026-48521
Published: August 26, 2026
Vulnerability identifier: #VU145869
CSH Severity: Medium
CVSS v4: 8.2 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-48521
CWE-ID: CWE-476
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 a null pointer dereference in ProdClusterManagerFactory::allocateConnPool when selecting an HTTP/3 connection pool with a null transport_socket_options pointer. A remote attacker can send routine traffic that reaches a vulnerable cluster configuration to cause a denial of service.
Only deployments using auto_config with HTTP/3 in the protocol set are vulnerable, and the issue is reachable when a LoadBalancerContext returns no upstream transport-socket options, such as in synthetic, mirror, health-check, or async-client side calls.
Affected software
envoy
Istio
Istio
How to mitigate CVE-2026-48521
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