CVE-2026-4438: gethostbyaddr and gethostbyaddr_r return invalid DNS hostnames

Overview

Severity

Medium (CVSS 5.9)

CVSS Vector

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

Exploit Status

Not Exploited

Patch Tuesday

2026-Mar

Released

2026-03-22

Last Updated

2026-03-31

EPSS Score

0.04% (percentile: 13.6%)

Affected Products (3)

Open Source Software

• azl3 glibc 2.38-19 on Azure Linux 3.0
• azl3 glibc 2.38-18 on Azure Linux 3.0
• cbl2 glibc 2.35-10 on CBL Mariner 2.0

Revision History

• 2026-03-22: Information published.
• 2026-03-23: Information published.
• 2026-03-25: Information published.
• 2026-03-28: Information published.
• 2026-03-31: Information published.