CVE-2026-4437
Received Received - Intake

DNS Response Validation Bypass in GNU C Library gethostbyaddr Functions

Publication date: 2026-03-20

Last updated on: 2026-04-07

Assigner: GNU C Library

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.

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Meta Information

Published
2026-03-20
Last Modified
2026-04-07
Generated
2026-07-06
AI Q&A
2026-03-20
EPSS Evaluated
2026-07-05
NVD
CVE-2026-4437
EUVD
EUVD-2026-13796

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
gnu glibc From 2.34 (inc) to 2.43 (inc)

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Exploitability

CWE
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KEV
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CWE ID Description
CWE-125 The product reads data past the end, or before the beginning, of the intended buffer.

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Executive Summary

This vulnerability occurs in the GNU C Library versions 2.34 to 2.43 when the functions gethostbyaddr or gethostbyaddr_r are called with a configured nsswitch.conf that specifies the library's DNS backend. A crafted response from the configured DNS server can cause a violation of the DNS specification, leading the application to mistakenly treat a non-answer section of the DNS response as a valid answer.

Impact Analysis

The impact of this vulnerability is that an application relying on gethostbyaddr or gethostbyaddr_r may accept incorrect DNS responses as valid. This could potentially lead to incorrect hostname resolutions, which might affect application behavior, security decisions, or network communications.

Compliance Impact

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