---
id: CVE-2026-33630
title: c-ares is an asynchronous resolver library
summary: >-
  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
  channe…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-415
  - CWE-416
published: '2026-09-03'
updated: '2026-09-09'
sourceUpdated: '2026-09-09T21:09:13.080'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-33630'
references:
  - url: >-
      https://github.com/c-ares/c-ares/commit/1fa3b86a0b8d18fe7b60f3228a01d770feb026bc
    label: security-advisories@github.com
  - url: >-
      https://github.com/c-ares/c-ares/commit/d823199b688052dcdc1646f2ab4cb8c16b1c644a
    label: security-advisories@github.com
  - url: 'https://github.com/c-ares/c-ares/pull/1237'
    label: security-advisories@github.com
  - url: 'https://github.com/c-ares/c-ares/releases/tag/v1.34.7'
    label: security-advisories@github.com
  - url: 'https://github.com/c-ares/c-ares/security/advisories/GHSA-6wfj-rwm7-3542'
    label: security-advisories@github.com
tags:
  - nvd
epss: 0.00845
epssPercentile: 0.56152
ingestedAt: '2026-09-05T20:44:37.706Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.