Use-after-free in envoy - #VU119718
Published: December 10, 2025
Vulnerability identifier: #VU119718
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: N/A
CWE-ID: CWE-416
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to perform a denial of service attack
The vulnerability exists due to a use-after-free error during the ares_getaddrinfo query lifecycle when processing a specific sequence of DNS responses. A remote attacker can send a specially crafted DNS response to the application and perform a denial of service attack.
Note, the vulnerability exists due to usage of the vulnerable c-ares library - #VU119383 (CVE-2025-6240).
Affected software
envoy
Remediation
Install updates from vendor's website.
envoy - addressed in versions 1.33.13, 1.34.11, 1.35.7, 1.36.3