NULL pointer dereference in envoy - CVE-2026-47221
Published: June 24, 2026
Vulnerability identifier: #VU135115
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-2026-47221
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 the router filter when handling HTTP 303 internal redirects for body-less non-GET/HEAD requests. A remote attacker can send a specially crafted request to cause a denial of service.
Exploitation requires a route configured with an internal redirect policy that includes 303 in redirect_response_codes, and an upstream response with HTTP 303.
Affected software
envoy
How to mitigate CVE-2026-47221
Install security update from vendor's website.
envoy - addressed in versions 1.35.12, 1.36.8, 1.37.4, 1.38.2