Double Free Affecting c-ares package, versions <1.34.6-1ubuntu0.1


Severity

Recommended
medium

Based on Ubuntu security rating.

Threat Intelligence

EPSS
0.84% (57th percentile)

Do your applications use this vulnerable package?

In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.

Test your applications
  • Snyk IDSNYK-UBUNTU2604-CARES-17909669
  • published30 Sept 2026
  • disclosed3 Sept 2026

Introduced: 3 Sep 2026

CVE-2026-33630  (opens in a new tab)
CWE-415  (opens in a new tab)
CWE-416  (opens in a new tab)

How to fix?

Upgrade Ubuntu:26.04 c-ares to version 1.34.6-1ubuntu0.1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream c-ares package and not the c-ares package as distributed by Ubuntu. See How to fix? for Ubuntu:26.04 relevant fixed versions and status.

c-ares is an asynchronous resolver library. From ver 1.32.3 until 1.34.7, a use-after-free / double-free in c-ares' query-completion handling. The same flaw — a query's callback being invoked while the query is still linked in the channel's internal lookup structures — is present at multiple points in the resend/finish path (timeout handling, response handling, and query dispatch). If the query, or for ares_getaddrinfo() the owning host_query, is freed as a side effect of that callback, it is then accessed and/or freed a second time. This vulnerability is fixed in ver 1.34.7.

CVSS Base Scores

version 3.1