CVE-2026-4437

HIGH

gethostbyaddr and gethostbyaddr_r may incorrectly handle DNS response

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, 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.

References (1)

https://sourceware.org/bugzilla/show_bug.cgi?id=34014

Scores

CVSS v3 7.5

EPSS 0.0007

EPSS Percentile 20.8%

Attack Vector NETWORK

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

CISA SSVC

Vulnrichment

Exploitation none

Automatable yes

Technical Impact partial

Details

CWE

CWE-125

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