CVE-2026-89092

Stack overflow in nscd due to unbounded alloca use

Published Sep 11, 2026 CVSS 3.1 · 4.2 Medium EPSS < 1% KEV · Not listed
Description
The nscd service in the GNU C Library 2.3.4 onwards may crash due to a
stack overflow when a malicious DNS server returns too large a response
for a DNS query, resulting in degraded DNS resolution for the system.



Exploitation of this bug needs a system that has nscd enabled and using
an untrusted DNS server for name resolution, with the compromised DNS
server being capable of processing records large enough to result in a
stack overflow in an nscd thread stack.  During experimentation, bind 9
was unable to handle large records, but that could change in future or
with a different name server.  In typical installations, nscd is
executed in an isolated context as its own user without a shell, due to
which any compromise of that service is isolated.



There is a remote possibility of nscd cache corruption if an attacker
manages to get the stack pointer into a desired point in the heap,
potentially resulting in other caches in nscd being overwritten with
corrupt data through the stack overflow, until the buggy code path
eventually results in a crash.



Finally, a crash in nscd may result in performance degradation when
resolving names, but it does not result in a denial of service.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Ubuntu USN Ubuntu USN USN-9065-1 GNU C Library vulnerabilities
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared The Gnu C Library
The Gnu C Library glibc
Vendors & Products The Gnu C Library
The Gnu C Library glibc
Type Values Removed Values Added
Description The nscd service in the GNU C Library 2.3.4 onwards may crash due to a stack overflow when a malicious DNS server returns too large a response for a DNS query, resulting in degraded DNS resolution for the system. Exploitation of this bug needs a system that has nscd enabled and using an untrusted DNS server for name resolution, with the compromised DNS server being capable of processing records large enough to result in a stack overflow in an nscd thread stack.  During experimentation, bind 9 was unable to handle large records, but that could change in future or with a different name server.  In typical installations, nscd is executed in an isolated context as its own user without a shell, due to which any compromise of that service is isolated. There is a remote possibility of nscd cache corruption if an attacker manages to get the stack pointer into a desired point in the heap, potentially resulting in other caches in nscd being overwritten with corrupt data through the stack overflow, until the buggy code path eventually results in a crash. Finally, a crash in nscd may result in performance degradation when resolving names, but it does not result in a denial of service.
Title Stack overflow in nscd due to unbounded alloca use
Weaknesses CWE-789
References
Metrics cvssV3_1

{'score': 4.2, 'vector': 'CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:L'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
glibc
Published
Updated
Sep 11, 2026, 5:02 PM
Reserved
Sep 10, 2026, 8:18 PM
Status
Awaiting Analysis
Published
Sep 11, 2026, 2:18 AM
Modified
Oct 26, 2026, 11:10 PM
Severity
Moderate
Public date
Sep 11, 2026, 1:23 AM