A use-after-free vulnerability in the Linux Kernel io_uring subsystem can be exploited to achieve local privilege escalation. Racing a io_uring cancel poll request with a linked timeout can cause a UAF in a hrtimer. We recommend upgrading past commit ef7dfac51d8ed961b742218f526bd589f3900a59 (4716c73b188566865bdd79c3a6709696a224ac04 for 5.10 stable and 0e388fce7aec40992eadee654193cad345d62663 for 5.15 stable).
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.