CVE-2026-52919
HighCVSS 7.8Exploitation Probability (EPSS)
Low risk2th percentile — higher than 2% of all known CVEs
Summary
In the Linux kernel, the batman-adv module's tp_meter counter can underflow during shutdown due to multiple callers decrementing the atomic counter. This causes a sender kthread to loop indefinitely, leading to a use-after-free when the interface is removed.
Risk Assessment
The organization faces system crashes or potential privilege escalation, as the vulnerability allows code execution in kernel context via a use-after-free bug.
Recommendation
Immediately update the Linux kernel to a version containing the fix (commit with atomic_xchg()) that prevents counter underflow and eliminates the race condition.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: batman-adv: fix tp_meter counter underflow during shutdown batadv_tp_sender_shutdown() unconditionally decrements the "sending" atomic counter. If multiple paths (e.g. timeout, user cancel, and normal finish) call this function, the counter can underflow to -1. Since the sender logic treats any non-zero value as "still sending", a negative value causes the sender kthread to loop indefinitely. This leads to a use-after-free when the interface is removed while the zombie thread is still active. Fix this by using atomic_xchg() to ensure the counter only transitions from 1 to 0 once. [sven: added missing change in batadv_tp_send]