An integer overflow vulnerability exists in Corosync's join message sanity validation in Red Hat Enterprise Linux 10. This flaw allows remote attackers to send specially crafted UDP packets that cause the Corosync service to crash, leading to denial of service. The issue specifically impacts Corosync configured with totemudp/totemudp mode. Red Hat has issued security advisories (RHSA-2026:13644 and RHSA-2026:13657) providing updated Corosync packages that fix this vulnerability. The advisories cover multiple architectures and Red Hat Enterprise Linux versions 8 and 10. The vulnerability has a CVSS score of 7.5 and is rated as Moderate by Red Hat Product Security. No exploits in the wild are currently known.

Successful exploitation results in denial of service by crashing the Corosync service on affected Red Hat Enterprise Linux 10 systems. There is no impact on confidentiality or integrity reported. The vulnerability can be triggered remotely without authentication or user interaction, making it a high-risk availability issue. No known active exploitation has been observed.

Red Hat has released official security updates for Corosync that address this vulnerability. Users should apply the updated Corosync packages as detailed in Red Hat advisories RHSA-2026:13644 and RHSA-2026:13657. The advisories provide instructions and links for applying the patches on affected Red Hat Enterprise Linux 10 and 8 systems. Applying these updates fully mitigates the vulnerability. No additional mitigation actions are required beyond applying the vendor-provided patches.