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GNU C Library CVE-2026-6238

| EUVDEUVD-2026-26071 MEDIUM
Buffer Over-read (CWE-126)
2026-04-28 glibc
6.5
CVSS 3.1 · Vendor: glibc
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Severity by source

Vendor (glibc) PRIMARY
6.5 MEDIUM
AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L
vuln.today AI
4.8 MEDIUM

AC:H reflects the non-default prerequisite that the target application must explicitly call deprecated debug functions absent from any normal execution path.

3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L
4.0 AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N
SUSE
MEDIUM
qualitative
Red Hat
6.5 MEDIUM
qualitative

Primary rating from Vendor (glibc).

CVSS VectorVendor: glibc

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

Lifecycle Timeline

4
Analysis Generated
Jul 24, 2026 - 04:23 vuln.today
CVSS changed
Apr 28, 2026 - 22:22 NVD
6.5 (MEDIUM)
EUVD ID Assigned
Apr 28, 2026 - 18:45 euvd
EUVD-2026-26071
CVE Published
Apr 28, 2026 - 16:43 nvd
MEDIUM 6.5

DescriptionCVE.org

The deprecated functions ns_printrrf, ns_printrr and fp_nquery in the GNU C Library version 2.2 and newer fail to validate the RDATA content against the RDATA length in a DNS response when processing LOC, CERT, TKEY or TSIG records, which may allow an attacker to craft a DNS response, causing a target application to crash or read uninitialized memory.

These functions are for application debugging only and hence not in the path of code executed by the DNS resolver. Further, they have been deprecated since version 2.34 and should not be used by any new applications. Applications should consider porting away from these interfaces since they may be removed in future versions.

AnalysisAI

Deprecated DNS printing functions in glibc 2.2 and later fail to validate RDATA content length for LOC, CERT, TKEY, and TSIG record types, enabling an attacker who can supply a crafted DNS response to crash affected applications or leak uninitialized memory. The affected functions - ns_printrrf, ns_printrr, and fp_nquery - are explicitly debug-only utilities outside the standard DNS resolver code path, and have been formally deprecated since glibc 2.34, substantially limiting real-world exposure. No public exploits or active exploitation have been identified (SSVC Exploitation: none; EPSS: 0.04%), and a vendor patch is available via the glibc project and Red Hat advisory RHSA-2026:12740.

Technical ContextAI

The vulnerability resides in three DNS-formatting utility functions in the GNU C Library (CPE: cpe:2.3:a:the_gnu_c_library:glibc:*:*:*:*:*:*:*:*) present since version 2.2. These functions parse DNS resource record wire-format data for display and debugging purposes but fail to cross-check the RDATA content length field against the actual bytes available in the buffer. CWE-126 (Buffer Over-Read) describes this class of flaw precisely: the code reads beyond the intended buffer boundary, potentially exposing adjacent process memory. The flaw applies specifically to four DNS record types - LOC (geographic location), CERT (certificate data), TKEY (transaction key), and TSIG (transaction signature) - all of which carry variable-length RDATA payloads that must be bounds-checked. Critically, these functions are not part of the DNS resolver execution path and are not invoked during normal name resolution; they were deprecated in glibc 2.34, meaning any modern application following current practices would not call them.

RemediationAI

Apply the vendor-released patch referenced in glibc bug 34069 (https://sourceware.org/bugzilla/show_bug.cgi?id=34069) and the libc-announce notification (https://inbox.sourceware.org/libc-announce/7a655d55-276f-41fe-b550-feb3ebb2ce91@redhat.com/T/#u). Red Hat users should apply the update from advisory RHSA-2026:12740 at https://access.redhat.com/errata/RHSA-2026:12740. Siemens product users should consult https://cert-portal.siemens.com/productcert/html/ssa-082556.html for product-specific guidance. The exact fixed glibc release version was not confirmed from available references - verify the specific package version with your distribution's security advisory. As a higher-priority compensating control, audit all application codebases for direct calls to ns_printrrf, ns_printrr, or fp_nquery and remove or replace them with supported alternatives; this is also the upstream vendor's recommended long-term action, as these functions may be removed entirely in a future glibc release. Note that updating glibc is a system-level operation that requires careful regression testing since virtually all userspace applications link against it.

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Vendor StatusVendor

SUSE

Severity: Medium
Product Status
SLES15-SP5-CHOST-BYOS-SAP-CCloud Fixed
SLES15-SP6-CHOST-BYOS Fixed
SLES15-SP6-CHOST-BYOS-Aliyun Fixed
SLES15-SP6-CHOST-BYOS-Azure Fixed
SLES15-SP6-CHOST-BYOS-EC2 Fixed

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CVE-2026-6238 vulnerability details – vuln.today

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