CVE-2026-53260

A flaw was found in the Linux kernel's TCP request socket path. A race condition can occur on PREEMPT_RT kernels when the reqsk_queue_hash_req function is preempted after setting a timer but before initializing a reference count. If a timer fires during this window while the listener is closing, it can lead to a reference count underflow and a use-after-free condition. This vulnerability could allow a remote attacker to cause a denial of service through a kernel crash or potentially achieve kernel memory corruption, impacting system confidentiality and integrity.

This vulnerability is rated Moderate impact by Red Hat because triggering the flaw requires an active real-time preemption configuration (PREEMPT_RT) along with precise timing between socket closure and timer expiration. Standard kernel installations are unaffected by default as they run without full real-time preemption enabled. Furthermore, older enterprise platforms including Enterprise Linux 8 and 9 lack the introducing code and are entirely unaffected. Exploitation on susceptible real-time systems could result in kernel memory corruption and denial of service.

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.