CVE-2026-49422
HighCVSS 8.4Exploitation Probability (EPSS)
Low risk4th percentile - higher than 4% of all known CVEs
Summary
The RACK setsockopt(2) handler drops the connection lock in order to copy option data from userspace, then reacquires the lock. After reacquiring, it verifies that the TCP stack had not been switched away, but did not reload its pointer to the stack's per-connection control block. If userspace switches stacks twice during this window, the check will succeed but the saved pointer will refer to freed memory. The bug may be exploitable by an unprivileged local user to escalate privileges.
Risk Assessment
Use of freed memory may allow an unprivileged user to escalate privileges and gain control of the system.
Recommendation
Apply the vendor patch that ensures the pointer to the control block is reloaded after reacquiring the lock. Update the system to a patched version.
Original NVD description (English source)
The RACK setsockopt(2) handler drops the connection lock in order to copy option data from userspace, then reacquires the lock. After reacquiring, it verifies that the TCP stack had not been switched away, but did not reload its pointer to the stack's per-connection control block. If userspace switches stacks twice during this window, the check will succeed but the saved pointer will refer to freed memory. The bug may be exploitable by an unprivileged local user to escalate privileges.