CVE-2026-4438

MEDIUM

gethostbyaddr and gethostbyaddr_r return invalid DNS hostnames

Title source: cna

Description

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 result in an invalid DNS hostname being returned to the caller in violation of the DNS specification.

References (1)

https://sourceware.org/bugzilla/show_bug.cgi?id=34015

Scores

CVSS v3 5.4

EPSS 0.0004

EPSS Percentile 13.7%

Attack Vector ADJACENT_NETWORK

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

CISA SSVC

Vulnrichment

Exploitation none

Automatable no

Technical Impact partial

Details

CWE

CWE-20 CWE-88

Status published

Products (2)

gnu/glibc 2.34 - 2.43

The GNU C Library/glibc 2.34 - 2.43

Published Mar 20, 2026

Tracked Since Mar 21, 2026