CVE-2026-4437: GNU Glibc

High severity, CVSS 7.5. EPSS: 0.3% chance of exploitation in the next 30 days.

Calling gethostbyaddr or gethostbyaddr_r with a configured nsswitch.conf that specifies the library's DNS backend in the GNU C Library version 2.34 to version 2.43 could, with a crafted response from the configured DNS server, result in a violation of the DNS specification that causes the application to treat a non-answer section of the DNS response as a valid answer.

Affected products

• GNU Glibc: from 2.34, up to and including 2.43

Published 2026-03-20. Last modified 2026-07-14.