Bug 2449777 (CVE-2026-4437)

Summary: CVE-2026-4437 glibc: glibc: Incorrect DNS response parsing via crafted DNS server response
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: ashankar, codonell, dj, fweimer, pfrankli
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in glibc (the GNU C Library). When an application uses the `gethostbyaddr` or `gethostbyaddr_r` functions with a `nsswitch.conf` configuration that specifies glibc's DNS backend, a remote attacker can send a specially crafted DNS (Domain Name System) response. This crafted response can cause the application to incorrectly interpret a non-answer section of the DNS response as a valid answer, leading to potential misbehavior or incorrect information processing.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On: 2450232, 2450236, 2450228, 2450230, 2450234, 2450237    
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Description OSIDB Bzimport 2026-03-20 21:02:13 UTC
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.