DNS Response Handling Flaw in GNU C Library by GNU
CVE-2026-4437

7.5HIGH

Key Information:

Vendor

The Gnu C Library

Status
Glibc
Vendor
CVE Published:
20 March 2026

What is CVE-2026-4437?

The GNU C Library is vulnerable to a flaw that arises when interacting with a DNS server configured in the nsswitch.conf file. Specifically, functions like gethostbyaddr or gethostbyaddr_r may not properly handle crafted DNS responses, resulting in a situation where a non-answer section is incorrectly categorized as a valid answer. This compromise can lead to unexpected application behavior and violation of DNS protocol specifications, particularly in handling DNS data integrity.

Affected Version(s)

glibc 2.34 <= 2.43

References

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

CVSS V3.1

Score:
7.5
Severity:
HIGH
Confidentiality:
None
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Antonio Maini (0rbitingZer0) - 0rbitingZer0@proton.me
Kevin Farrell
.