CVE-2026-89092: the gnu c library glibc

Vulnerability summary

CVE-2026-89092 is a medium (CVSS 4.2) vulnerability in the gnu c library glibc. EPSS estimates a 0.24% chance of exploitation in the next 30 days, higher than 14.1% of scored vulnerabilities.

Timeline

1. 11-09-2026
   PublishedVulnerability first disclosed.
2. 11-09-2026
   Last modifiedVulnerability information updated.

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.

• CWE-789Memory Allocation with Excessive Size ValueThe product allocates memory based on an untrusted, large size value, but it does not ensure that the size is within expected limits, allowing arbitrary amounts of memory to be allocated.