The vulnerability CVE-2026-89092 in glibc's nscd service arises from improper handling of large DNS responses, causing a stack overflow. When a malicious DNS server returns a response too large for nscd's stack, it may overflow the stack, potentially corrupting internal caches and eventually crashing the service. This affects glibc versions >=2.3.4 and <2.45. Exploitation requires nscd enabled and using an untrusted DNS server. The impact is limited to degraded DNS resolution performance due to nscd crashes. The nscd service runs in an isolated context with no shell access, limiting the scope of compromise. There is no indication of remote code execution or denial of service beyond performance degradation.

Successful exploitation causes nscd to crash due to stack overflow, resulting in degraded DNS resolution performance on the affected system. There is a remote possibility of nscd cache corruption, which could lead to overwriting of other caches with corrupt data until a crash occurs. The vulnerability does not cause a full denial of service and does not compromise system confidentiality or availability beyond degraded DNS resolution. The isolated execution context of nscd limits the potential impact of any compromise.

No official patch or fix is currently confirmed for this vulnerability. Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Mitigation includes ensuring that nscd is not configured to use untrusted DNS servers, or disabling nscd if it is not required. Monitoring and restricting DNS server configurations to trusted sources can reduce exposure. Since nscd runs isolated with limited privileges, the risk of further compromise is reduced.