CVE-2026-89092

A flaw was found in glibc, specifically within the nscd service. A remote attacker, operating a malicious Domain Name System (DNS) server, could send an overly large DNS response. This could trigger a stack overflow in the nscd service, causing it to crash and leading to degraded DNS resolution for the system. There is also a remote possibility of nscd cache corruption.

A flaw of moderate impact was found in the nscd service of the GNU C Library (glibc), as shipped in Red Hat Enterprise Linux and in the Red Hat OpenShift Container Platform core images that embed RHEL components. A remote attacker controlling a malicious or compromised DNS server used by a system with nscd enabled could return an overly large DNS response to a query, triggering a stack overflow in an nscd thread that crashes the service and degrades DNS name resolution for the system. Exploitation requires an adjacent network position and is difficult in practice: the attacker must operate the DNS server the victim uses for name resolution, and that server must be capable of processing DNS records large enough to overflow an nscd thread stack. There is also a remote possibility of nscd cache corruption. In typical installations nscd runs in an isolated context as its own user without a shell, which limits the impact of any compromise, and a crash causes performance degradation when resolving names rather than a denial of service of the whole system. The Red Hat severity (Moderate, CVSS 4.2, CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:L) is aligned with the upstream glibc advisory. For most affected Red Hat Enterprise Linux and OpenShift Container Platform streams the fix is deferred because the issue is rated Moderate with a CVSS score below the threshold that warrants active remediation, leaving the residual risk that affected systems with nscd enabled and relying on an untrusted DNS server could experience repeated nscd crashes and degraded name resolution. A fix is being pursued for the remaining delegated affected streams, while certain newer streams were assessed as not affected.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.