CVE-2026-4437 Details
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.
A vulnerability exists in the GNU C Library (glibc) versions 2.34 through 2.43, specifically within the Name Service Switch (NSS) component. The issue arises when the gethostbyaddr or gethostbyaddr_r functions are called with a nsswitch.conf configuration that directs DNS queries to the library's DNS backend. Under these conditions, a crafted response from the DNS server could lead to a misinterpretation of the DNS response sections. This flaw allows the application to incorrectly treat a non-answer section as a valid answer, potentially returning an incorrect hostname to the caller.
A patch for this vulnerability has been developed and is available. The patch has been posted to the libc-alpha mailing list.
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CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed Mar 23, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://cert-portal.siemens.com/productcert/html/ssa-082556.html | siemens-SADP | |
| https://sourceware.org/bugzilla/show_bug.cgi?id=34014 | GNU C Library | ExploitIssue TrackingPatch |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-125 | Out-of-bounds Read | GNU C Library |
Affected Products
| Product | Versions |
|---|---|
| gnu glibc | >= 2.34, <= 2.43 |
CPE
Remediation
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Change History
6 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 14, 2026 | CVE Modified | siemens-SADP |
| Jun 17, 2026 | CVE Modified | GNU C Library |
| Jun 17, 2026 | CVE Modified | CISA-ADP |
| Apr 7, 2026 | Initial Analysis | [email protected] |
| Mar 23, 2026 | CVE Modified | CISA-ADP |
| Mar 20, 2026 | New CVE Received | GNU C Library |