CVE-2025-71080

A race condition vulnerability was found in the Linux kernel's IPv6 routing subsystem on PREEMPT_RT kernels. When rt6_get_pcpu_route() returns NULL and the task is preempted, another task can install a per-CPU route entry. When the original task resumes and attempts cmpxchg() in rt6_make_pcpu_route(), the operation fails because the pointer is no longer NULL, triggering a BUG_ON crash.

This vulnerability specifically affects PREEMPT_RT (real-time) kernel configurations during IPv6 routing operations. Standard kernel builds are not affected as the race window does not exist without RT preemption. The crash requires specific timing conditions and concurrent IPv6 route operations on the same CPU.

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.