CVE-2026-69186
Publication date 18 September 2026
Last updated 21 October 2026
Ubuntu priority
Description
c-ares is an asynchronous resolver library. Prior to 1.34.7, ares_dns_parse() trusts the attacker-controlled ANCOUNT, NSCOUNT, and ARCOUNT fields before confirming that the DNS response contains enough bytes for the claimed records. Because process_answer() invokes parsing before transaction ID and question validation, a malicious DNS response can cause ares_dns_record_rr_prealloc() and ares_array_set_size() to reserve disproportionate heap memory for a tiny message. Repeated responses create large allocation and release cycles that can degrade or deny name resolution, without causing memory corruption or information disclosure. This issue is fixed in version 1.34.7.
Status
| Package | Ubuntu Release | Status |
|---|---|---|
| c-ares | 26.10 stonking |
Not affected
|
| 26.04 LTS resolute |
Fixed in 1.34.6-1ubuntu0.2
|
|
| 24.04 LTS noble |
Fixed in 1.27.0-1.0ubuntu1.1
|
|
| 22.04 LTS jammy |
Not affected
|
|
| 20.04 LTS focal |
Not affected
|
|
| 18.04 LTS bionic |
Not affected
|
|
| 16.04 LTS xenial |
Not affected
|
Severity score breakdown
CVSS version: CVSS v3.0
Base score
5.3 · Medium
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
References
Related Ubuntu Security Notices (USN)
- USN-8951-1
- c-ares vulnerabilities
- 21 October 2026