CVE-2026-45927

A flaw was found in the Linux kernel's Berkeley Packet Filter (BPF) subsystem. This vulnerability, a Time-of-check to time-of-use (TOCTOU) bug, allows a local attacker to modify the contents of a BPF map after its hash has been calculated but before it is frozen. Consequently, a trusted loader could be deceived into verifying an outdated hash, leading to the loading of potentially malicious or unauthorized code. This could compromise the integrity of the system.

The default Red Hat Enterprise Linux kernel prevents unprivileged users from being able to use eBPF by the kernel.unprivileged_bpf_disabled sysctl. This would require a privileged user with CAP_SYS_ADMIN or root to be able to abuse this flaw reducing its attack space.

For the Red Hat Enterprise Linux 9 to confirm the current state, inspect the sysctl with the command:

cat /proc/sys/kernel/unprivileged_bpf_disabled

The setting of 1 would mean that unprivileged users can not use eBPF, mitigating the flaw.

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.