gethostbyaddr and gethostbyaddr_r may incorrectly handle DNS response

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Summary

CVECVE-2026-4437
StatePUBLISHED
Assignerglibc
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-03-20 20:16:49 UTC
Updated2026-04-07 18:41:36 UTC
DescriptionCalling 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.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from ADP

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

EPSS: 0.000520000 probability, percentile 0.163790000 (date 2026-04-07)

Problem Types: CWE-125 | CWE-125 CWE-125 Out-of-bounds read

VersionSourceTypeScoreSeverityVector
3.1ADPDECLARED7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1134c704f-9b21-4f2e-91b3-4a467353bcc0Secondary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

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

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Gnu Glibc All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA The GNU C Library Glibc affected 2.34 2.43 custom Not specified

References

ReferenceSourceLinkTags
sourceware.org/bugzilla/show_bug.cgi 3ff69d7a-14f2-4f67-a097-88dee7810d18 sourceware.org Exploit, Issue Tracking, Patch
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Antonio Maini (0rbitingZer0) - [email protected] (en)

CNA: Kevin Farrell (en)

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