CVE-2026-72118 can: bcm: fix CAN frame rx/tx statistics
A race condition in the Linux kernel CAN BCM module allows concurrent CPUs to corrupt statistics, potentially exposing incorrect data via procfs.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-72118?
CVE-2026-72118 is a vulnerability in Linux, published on 15 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
can: bcm: fix CAN frame rx/tx statistics
KCSAN detected a data race within the bcm_rx_handler() when two CAN frames have been simultaneously received and processed in a single rx op by two different CPUs.
Use atomic operations with (signed) long data types to access the statistics in the hot path to fix the KCSAN complaint.
Additionally simplify the update and check of statistics overflow by using the atomic operations in separate bcm_update_[rx|tx]_stats() functions. The rx variant runs under bcm_rx_update_lock to prevent races when resetting the two rx counters; the tx variant runs under bcm_tx_lock and only needs to guard its own counter's overflow.
As the rx path resets its values already at LONG_MAX / 100, there is no conflict between the two locking domains (bcm_rx_update_lock vs. bcm_tx_lock) even for ops that use both paths.
The rx statistics update and the frames_filtered update in bcm_rx_changed() were previously performed in two separate bcm_rx_update_lock sections. For an rx op subscribed on all interfaces (ifindex == 0), bcm_rx_handler() can run concurrently on different CPUs, so a counter reset by one CPU between these two sections could leave frames_filtered larger than frames_abs on another CPU, producing a bogus (even negative) reduction percentage in procfs. Update the statistics in the same critical section as bcm_rx_changed() to close this gap, which also removes the now unneeded extra lock/unlock pair around the traffic_flags calculation.
Which versions are affected by CVE-2026-72118?
How do I fix CVE-2026-72118?
Apply the vendor's patch.
Is CVE-2026-72118 being exploited?
There is no known exploitation of CVE-2026-72118 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-72118, DEBIAN-CVE-2026-72118, GHSA-5pqf-xwxg-479q, UBUNTU-CVE-2026-72118.