High severity · published Sep 3, 2026
CVE-2026-33630
c-ares : Use-after-free / double-free in c-ares query-completion handling, remotely triggerable via ares_getaddrinfo() over TCP
7.5
CVSS
0.8%
EPSS
No
On KEV
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 vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.8% · higher than 58% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
CA
c-ares · c-ares
>= 1.32.3, < 1.34.7 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-33630
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-33630
github.com
https://github.com/c-ares/c-ares/commit/1fa3b86a0b8d18fe7b60f3228a01d770feb026bc
github.com
https://github.com/c-ares/c-ares/commit/d823199b688052dcdc1646f2ab4cb8c16b1c644a
github.com
https://github.com/c-ares/c-ares/pull/1237
github.com
https://github.com/c-ares/c-ares/releases/tag/v1.34.7
github.com
https://github.com/c-ares/c-ares/security/advisories/GHSA-6wfj-rwm7-3542
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