CVE-2021-47303

A flaw was found in the Linux kernel's Berkeley Packet Filter (BPF) subsystem. A local user with permissions to load BPF programs can exploit this vulnerability to cause a Denial of Service (DoS) through a system crash, or potentially achieve privilege escalation. The issue arises from a use-after-free condition where the kernel fails to untrack program descriptors when releasing subprograms, leaving stale references to memory that has already been deallocated. Subsequent operations that access these dangling references result in invalid memory operations that destabilize the operating system.

This vulnerability is rated as Low impact for Red Hat Enterprise Linux because exploitation requires loading specialized eBPF programs, an operation restricted to privileged accounts possessing CAP_BPF or CAP_SYS_ADMIN by default. On standard Red Hat deployments, unprivileged eBPF is disabled out of the box, preventing unprivileged local users from triggering this use-after-free condition. Consequently, the flaw presents limited practical risk beyond a denial of service initiated by an already privileged user.

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.