MIT Kerberos 5, a network authentication protocol implementation, contains multiple vulnerabilities that can cause denial of service. Specifically, CVE-2026-40356 involves an integer underflow and out-of-bounds read, while CVE-2026-40355 involves a NULL pointer dereference in the NegoEx mechanism. These flaws can be triggered to crash or disrupt the Kerberos service. Red Hat has issued security advisories and updates for affected packages in Red Hat Enterprise Linux 8 and hardened images to remediate these issues.

Successful exploitation of these vulnerabilities results in denial of service conditions, potentially disrupting authentication services that rely on MIT Kerberos 5. This can affect network security and availability but does not indicate remote code execution or data compromise based on the provided data.

Red Hat has released official security updates that fix these vulnerabilities in MIT Kerberos 5 packages for Red Hat Enterprise Linux 8 and hardened images. Users should apply these updates promptly. For detailed update instructions, refer to the Red Hat advisories at https://access.redhat.com/errata/RHSA-2026:12220 and https://access.redhat.com/errata/RHSA-2026:16799. No additional mitigation is indicated by the vendor advisory.