Inefficient Algorithmic Complexity in c-ares - CVE-2026-69184
Published: July 7, 2026 / Updated: September 22, 2026
Vulnerability identifier: #VU137034
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: CVE-2026-69184
CWE-ID: CWE-407
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 inefficient algorithmic complexity in ares_dns_name_parse() when parsing crafted DNS responses with unbounded compression pointer chains. A remote attacker can send a specially crafted DNS response to cause a denial of service.
Because c-ares runs on a single-threaded event loop, parsing a crafted response can stall all resolution for the duration.
Affected software
c-ares
How to mitigate CVE-2026-69184
Install security update from vendor's website.
c-ares - update to 1.34.7