CVE intelligence

CVE-2026-4438

Vulnerability intelligence

Published Mar 20, 2026Sources checked Oct 3, 2026

5.4MEDIUMCVSS out of 10

What this means

Review the available evidence

CVE-2026-4438 and is rated Medium severity with a CVSS score of 5.4. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.

What to do next

Remediation and response

Microsoft Security Response Center guidance

CBL-Mariner Releases

Vendor-listed releases

2.38-19

CISA KEVNot listedBased on the latest collected catalog

EPSS0.3%Estimated 30-day exploitation probability

Ransomware useNot markedCISA KEV ransomware field

Threat actors0Source-linked actor relationships

Overview

What is CVE-2026-4438?

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.