Important: kernel update

This advisory covers multiple kernel vulnerabilities fixed in Red Hat Enterprise Linux 8.4. CVE-2026-43499 addresses an issue in the rtmutex code where waiter::task is now used instead of current in remove_waiter(), preventing potential misuse. CVE-2026-53166 fixes a NULL pointer dereference in futex/requeue during self-deadlock conditions. Additionally, a kernel flaw causing XFS filesystem data corruption when using reflink has been corrected. These vulnerabilities have a CVSS 3.1 base score indicating high severity with impacts on confidentiality, integrity, and availability. The vendor advisory confirms that updated kernel packages are available and that a reboot is required to apply the fixes.

The vulnerabilities allow for potential privilege escalation or denial of service due to kernel memory corruption or NULL pointer dereference. The XFS data corruption issue could lead to loss or corruption of filesystem data. The CVSS vector indicates local attack vector with low complexity and no user interaction required, resulting in high impact on confidentiality, integrity, and availability.

Red Hat has released updated kernel packages for Red Hat Enterprise Linux 8.4 that address these vulnerabilities. Users should apply the security update as described in the Red Hat advisory RHSA-2026:39984 and reboot affected systems to ensure the fixes take effect. No additional mitigations are specified beyond applying the official update.