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.
Analysis
No analysis available yet.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||
|---|---|---|---|---|---|---|---|---|---|
| The GNU C Library | glibc | unaffected |
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Tracking
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Fri, 11 Sep 2026 01:30:00 +0000
| 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
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Subscriptions
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MITRE
Status: PUBLISHED
Assigner: glibc
Published:
Updated: 2026-09-11T01:23:01.162Z
Reserved: 2026-09-10T20:18:09.584Z
Link: CVE-2026-89092
Vulnrichment
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NVD
Status : Received
Published: 2026-09-11T02:18:35.460
Modified: 2026-09-11T02:18:35.460
Link: CVE-2026-89092
Redhat
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OpenCVE Enrichment
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CWE-789
Memory Allocation with Excessive Size Value