CVE-2026-89092
Stack overflow in nscd due to unbounded alloca use
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.
INFO
Published Date :
Sept. 11, 2026, 2:18 a.m.
Last Modified :
Oct. 26, 2026, 11:10 p.m.
Remotely Exploit :
No
Source :
3ff69d7a-14f2-4f67-a097-88dee7810d18
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | MEDIUM | 3ff69d7a-14f2-4f67-a097-88dee7810d18 |
Solution
- Update the GNU C Library.
- Disable nscd if not required.
- Configure nscd to use trusted DNS servers.
- Monitor DNS resolution performance.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-89092.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-89092 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-89092
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-89092 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-89092 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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CVE Translated by [email protected]
Oct. 26, 2026
Action Type Old Value New Value Added Translation Title: BIND 9 de ISC, Description: El servicio nscd en la Biblioteca C de GNU a partir de la versión 2.3.4 puede fallar debido a un desbordamiento de pila cuando un servidor DNS malicioso devuelve una respuesta demasiado grande para una consulta DNS, lo que provoca una degradación de la resolución DNS del sistema.\n\nExplotar este error requiere un sistema que tenga nscd habilitado y que utilice un servidor DNS no confiable para la resolución de nombres, con el servidor DNS comprometido capaz de procesar registros lo suficientemente grandes como para generar un desbordamiento de pila en la pila de un hilo de nscd. Durante la experimentación, bind 9 no pudo manejar registros grandes, pero eso podría cambiar en el futuro o con un servidor de nombres diferente. En instalaciones típicas, nscd se ejecuta en un contexto aislado como su propio usuario sin shell, por lo que cualquier compromiso de ese servicio queda aislado.\n\nExiste una posibilidad remota de corrupción de la caché de nscd si un atacante logra colocar el puntero de pila en un punto deseado del montículo, lo que podría resultar en que otras cachés en nscd sean sobrescritas con datos corruptos mediante el desbordamiento de pila, hasta que la ruta de código defectuosa finalmente provoque un fallo.\n\nFinalmente, un fallo en nscd puede provocar una degradación del rendimiento al resolver nombres, pero no genera una denegación de servicio. -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Sep. 11, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-89092', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-09-11T16:57:22.665457Z'} -
CVE Modified by af854a3a-2127-422b-91ae-364da2661108
Sep. 11, 2026
Action Type Old Value New Value Added Reference http://www.openwall.com/lists/oss-security/2026/09/11/2 -
New CVE Received by 3ff69d7a-14f2-4f67-a097-88dee7810d18
Sep. 11, 2026
Action Type Old Value New Value 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. Added CVSS V3.1 AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:L Added CWE CWE-789 Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/89xxx/CVE-2026-89092.json">CVE-2026-89092</a> Added Reference https://sourceware.org/bugzilla/show_bug.cgi?id=34624 Added Reference https://sourceware.org/git/?p=glibc.git;a=blob_plain;f=advisories/GLIBC-SA-2026-0016