NULL Pointer Dereference
In librt in the GNU C Library (aka glibc) in 2.34, "sysdeps/unix/sysv/linux/mq_notify.c" mishandles certain "NOTIFY_REMOVED" data, leading to a NULL pointer dereference. NOTE: this vulnerability was introduced as a side effect of the CVE-2021-33574 fix.
CWE-476 - NULL Pointer Dereference
A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit.