What’s Vulnerable › Vulnerabilities
CVE-2023-32067: 0-byte UDP payload DoS in c-ares
- Severity: high (CVSS 7.5 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 1.6% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2023-05-25 · updated 2026-06-17
- Weakness: CWE-400
Description
c-ares is an asynchronous resolver library. c-ares is vulnerable to denial of service. If a target resolver sends a query, the attacker forges a malformed UDP packet with a length of 0 and returns them to the target resolver. The target resolver erroneously interprets the 0 length as a graceful shutdown of the connection. This issue has been patched in version 1.19.1.
Affected products
- C-Ares Project C-Ares: before 1.19.1 — fixed in 1.19.1
- Debian Linux: 10.0, 11.0
- Fedoraproject Fedora: 37, 38
How to fix
Upgrade to a fixed version: C-Ares Project C-Ares 1.19.1. Check the vendor advisory for mitigations.
References
- https://github.com/c-ares/c-ares/releases/tag/cares-1_19_1
- https://github.com/c-ares/c-ares/security/advisories/GHSA-9g78-jv2r-p7vc
- https://lists.debian.org/debian-lts-announce/2023/06/msg00034.html
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/B5Z5XFNXTNPTCBBVXFDNZQVLLIE6VRBY/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/UBFWILTA33LOSV23P44FGTQQIDRJHIY7/
- https://security.gentoo.org/glsa/202310-09
- https://security.netapp.com/advisory/ntap-20240605-0004/
- https://www.debian.org/security/2023/dsa-5419
- https://github.com/c-ares/c-ares/releases/tag/cares-1_19_1
- https://github.com/c-ares/c-ares/security/advisories/GHSA-9g78-jv2r-p7vc
- https://lists.debian.org/debian-lts-announce/2023/06/msg00034.html
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/B5Z5XFNXTNPTCBBVXFDNZQVLLIE6VRBY/
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