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[USN-8844-1] c-ares vulnerability

Posted on 29 September 2026
Ubuntu Security

==========================================================================Ubuntu Security Notice USN-8844-1
September 29, 2026

c-ares vulnerability
==========================================================================
A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 26.04 LTS

Summary:

c-ares could be made to crash or run programs if it received specially
crafted network traffic.

Software Description:
- c-ares: library for asynchronous name resolution

Details:

It was discovered that c-ares incorrectly handled certain query completion
callbacks. An attacker could possibly use this issue to trigger a use-
after-free or double-free, resulting in a denial of service or arbitrary
code execution.

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 26.04 LTS
libcares2 1.34.6-1ubuntu0.1

In general, a standard system update will make all the necessary changes.

References:
https://ubuntu.com/security/notices/USN-8844-1
CVE-2026-33630

Package Information:
https://launchpad.net/ubuntu/+source/c-ares/1.34.6-1ubuntu0.1

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