CVE-2026-4437: CWE-125 Out-of-bounds read in The GNU C Library glibc
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.
AI Analysis
Technical Summary
CVE-2026-4437 is an out-of-bounds read vulnerability in GNU C Library (glibc) versions 2.34 when using gethostbyaddr or gethostbyaddr_r functions with a nsswitch.conf configured to use the library's DNS backend. A maliciously crafted DNS response that violates the DNS specification can cause the application to treat a non-answer section as a valid answer, leading to an out-of-bounds read. This vulnerability is identified as CWE-125 and has a CVSS 3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H), indicating network attack vector, low attack complexity, no privileges or user interaction required, unchanged scope, no confidentiality or integrity impact, but high impact on availability.
Potential Impact
The vulnerability can cause an out-of-bounds read in affected glibc versions, potentially leading to application crashes or denial of service, impacting availability. There is no reported impact on confidentiality or integrity. No known exploits in the wild have been reported.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, consider avoiding configurations that use the DNS backend in nsswitch.conf with affected glibc versions or implement network-level protections to filter malicious DNS responses.
CVE-2026-4437: CWE-125 Out-of-bounds read in The GNU C Library glibc
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.
CVSS v3.1
Score 7.5high
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-4437 is an out-of-bounds read vulnerability in GNU C Library (glibc) versions 2.34 when using gethostbyaddr or gethostbyaddr_r functions with a nsswitch.conf configured to use the library's DNS backend. A maliciously crafted DNS response that violates the DNS specification can cause the application to treat a non-answer section as a valid answer, leading to an out-of-bounds read. This vulnerability is identified as CWE-125 and has a CVSS 3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H), indicating network attack vector, low attack complexity, no privileges or user interaction required, unchanged scope, no confidentiality or integrity impact, but high impact on availability.
Potential Impact
The vulnerability can cause an out-of-bounds read in affected glibc versions, potentially leading to application crashes or denial of service, impacting availability. There is no reported impact on confidentiality or integrity. No known exploits in the wild have been reported.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, consider avoiding configurations that use the DNS backend in nsswitch.conf with affected glibc versions or implement network-level protections to filter malicious DNS responses.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- glibc
- Date Reserved
- 2026-03-19T19:55:42.906Z
- Cvss Version
- null
- State
- PUBLISHED
Threat ID: 69bda974e32a4fbe5fca0bba
Added to database: 03/20/2026, 20:09:24 UTC
Last enriched: 07/15/2026, 11:23:49 UTC
Last updated: 08/02/2026, 07:17:57 UTC
Views: 330
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