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Vulnerability record · CVE-2026-33630 · published 3 September 2026

CVE-2026-33630: Double free vulnerability

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.

7.5 CVSS 3.1 High EPSS 0.85% · top 43.7% CWE-415 · Double freeCWE-416 · Use after free Deferred
7.5CVSS 3.1 base score
0.85%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
5References
9 Sep 2026Last modified by NVD

Description

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:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

LinkTags
https://github.com/c-ares/c-ares/commit/1fa3b86a0b8d18fe7b60f3228a01d770feb026bc
https://github.com/c-ares/c-ares/commit/d823199b688052dcdc1646f2ab4cb8c16b1c644a
https://github.com/c-ares/c-ares/pull/1237
https://github.com/c-ares/c-ares/releases/tag/v1.34.7
https://github.com/c-ares/c-ares/security/advisories/GHSA-6wfj-rwm7-3542

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2026-33824Double free in Windows IKE Extension enables remote code executionA double free flaw (CWE-415) exists in the Windows IKE Extension, reachable over the network by an unauthenticated attacker. Successful exploitation …KEVEPSS 1.6%analysed7.0CVE-2025-62215Windows Kernel race condition and double free privilege escalationA race condition combined with a double free in the Windows Kernel lets a locally authenticated attacker corrupt kernel memory and elevate privileges…KEVEPSS 6.0%analysed8.8CVE-2014-0502Adobe Flash Player Double Free Enables Remote Code ExecutionAdobe Flash Player, Adobe AIR, and the AIR SDK contain a double free vulnerability (CWE-415) that allows remote attackers to execute arbitrary code. …KEVEPSS 25%analysed8.8CVE-2018-4990Adobe Acrobat and Reader double free allows code executionAdobe Acrobat and Reader contain a double free (CWE-415) in versions 2018.011.20038 and earlier, 2017.011.30079 and earlier, and 2015.006.30417 and e…KEVEPSS 36%analysed7.0CVE-2021-22600Linux kernel af_packet double free allows local privilege escalationA double free bug in packet_set_ring() in net/packet/af_packet.c lets a local user trigger memory corruption through crafted syscalls. It matters bec…KEVEPSS 6.5%analysed7.8CVE-2020-9859Apple iOS, iPadOS, macOS, tvOS and watchOS double free allows kernel code executionA memory consumption issue in Apple's operating systems was caused by a double free (CWE-415) and fixed through improved memory handling. An applicat…KEVEPSS 0.83%analysed

Source: NIST National Vulnerability Database (record CVE-2026-33630), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.