CVE-2026-89092
Publication date 11 September 2026
Last updated 24 September 2026
Ubuntu priority
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.
Status
| Package | Ubuntu Release | Status |
|---|---|---|
| glibc | 26.04 LTS resolute |
Vulnerable, fix deferred
|
| 24.04 LTS noble |
Vulnerable, fix deferred
|
|
| 22.04 LTS jammy |
Vulnerable, fix deferred
|
|
| 20.04 LTS focal |
Vulnerable, fix deferred
|
|
| 18.04 LTS bionic |
Vulnerable, fix deferred
|
|
| 16.04 LTS xenial |
Vulnerable, fix deferred
|
|
| eglibc | 26.04 LTS resolute | Not in release |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 14.04 LTS trusty |
Vulnerable, fix deferred
|
Notes
Severity score breakdown
CVSS version: CVSS v3.0
Base score
4.2 · Medium
Vector: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:L