Assertion failure in the DNS stub resolver with a long search domain

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-8674
StatePUBLISHED
Assignerglibc
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-17 17:16:53 UTC
Updated2026-09-18 18:17:47 UTC
DescriptionInitializing the DNS stub resolver from an /etc/resolv.conf file, or a LOCALDOMAIN environment variable, whose search list contains a domain of roughly 200 characters or more in the GNU C Library version 2.26 to 2.44 results in an assertion failure which aborts the process. The resolver truncates the search list when copying it into the fixed-size _res.defdname buffer, then asserts that the copy is consistent with the full configuration. The consistency check compared against the wrong size and did not handle a first entry that does not fit, so a correctly truncated list failed the assertion. Any process that resolves names through the library is affected, including long-running processes that reload /etc/resolv.conf on the next query after it changes. Search domains are commonly written to /etc/resolv.conf from data received over DHCP or from a VPN server, so an attacker on the local network may be able to trigger this without privileges on the target system, subject to validation by the network configuration software.

Risk And Classification

Primary CVSS: v3.1 5.3 MEDIUM from 3ff69d7a-14f2-4f67-a097-88dee7810d18

CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS: 0.003060000 probability, percentile 0.236050000 (date 2026-09-18)

Problem Types: CWE-617 | CWE-617 CWE-617 Reachable Assertion

VersionSourceTypeScoreSeverityVector
3.13ff69d7a-14f2-4f67-a097-88dee7810d18Secondary5.3MEDIUMCVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1CNACVSS5.3MEDIUMCVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Adjacent
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA The GNU C Library Glibc affected 2.26 2.44 custom Not specified

References

ReferenceSourceLinkTags
sourceware.org/git 3ff69d7a-14f2-4f67-a097-88dee7810d18 sourceware.org
www.openwall.com/lists/oss-security/2026/09/17/4 af854a3a-2127-422b-91ae-364da2661108 www.openwall.com
sourceware.org/git 3ff69d7a-14f2-4f67-a097-88dee7810d18 sourceware.org
joshua.hu/fuzzing-glibc-libresolv 3ff69d7a-14f2-4f67-a097-88dee7810d18 joshua.hu
sourceware.org/bugzilla/show_bug.cgi 3ff69d7a-14f2-4f67-a097-88dee7810d18 sourceware.org
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Joshua Rogers (en)

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