CVE-2026-33630
Published: July 9, 2026Last modified: July 10, 2026
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.
Severity score breakdown
| Parameter | Value |
|---|---|
| Base score | 7.5 |
| Attack Vector | NETWORK |
| Attack complexity | LOW |
| Privileges required | NONE |
| User interaction | NONE |
| Scope | UNCHANGED |
| Confidentiality | NONE |
| Integrity impact | NONE |
| Availability impact | HIGH |
| Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
Status
| Product | Release | Package | Status |
|---|---|---|---|
| Alpaquita Linux | 23 LTS | c-ares | Not affected (1.18.1-r1) |
| 25 LTS | c-ares | Fixed (1.34.8-r0) | |
| Stream | c-ares | Fixed (1.34.8-r0) | |
| Hardened Containers | 25 LTS | c-ares | Fixed (1.34.8-r0) |
| Stream | c-ares | Fixed (1.34.8-r0) |
References
- 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