CVE-2026-72117
Received Received - Intake

Race Condition in Linux Kernel CAN BCM Module

Publication date: 2026-08-15

Last updated on: 2026-08-15

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: can: bcm: fix data race on rx_stamp/rx_ifindex in bcm_rx_handler() For an rx op subscribed on all interfaces (ifindex == 0), the same op is registered once in the shared per-netns wildcard filter list, so bcm_rx_handler() can run concurrently on different CPUs for frames arriving on different net devices. op->rx_stamp and op->rx_ifindex were written before bcm_rx_update_lock was taken, allowing concurrent writers to race each other - including a torn store of the 64-bit rx_stamp on 32-bit platforms. Beyond a torn store bcm_send_to_user() must report the timestamp/ifindex of the very same frame whose content it is delivering. So the assignment is placed in the same unbroken bcm_rx_update_lock section as the content comparison. As a side effect, the RTR-request frame feature (which never reach bcm_send_to_user()) no longer updates rx_stamp/rx_ifindex, since only the notification path needs them.

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Meta Information

Published
2026-08-15
Last Modified
2026-08-15
Generated
2026-08-15
AI Q&A
2026-08-15
EPSS Evaluated
N/A
NVD
CVE-2026-72117
EUVD
EUVD-2026-59075

Affected Vendors & Products

Currently, no data is known.

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Exploitability

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KEV
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This is a data race vulnerability in the Linux kernel's CAN BCM protocol implementation. It occurs when multiple CPUs concurrently process frames on different network devices for a subscription that listens on all interfaces. The race condition affects the rx_stamp and rx_ifindex fields, which can lead to torn writes on 32-bit systems and incorrect timestamp or interface reporting.

Detection Guidance

This vulnerability is specific to the Linux kernel's CAN BCM module and involves a data race condition. Detection requires checking kernel logs for related errors or kernel crashes, particularly involving the CAN subsystem. Commands like dmesg | grep -i can or journalctl -k | grep -i can may help identify issues. Ensure your kernel is updated to a patched version.

Impact Analysis

The vulnerability may cause incorrect timestamp or interface information to be reported for CAN frames, potentially leading to timing issues or misattribution of network traffic. On 32-bit systems, it could result in corrupted data due to torn writes. This primarily affects systems using the CAN BCM protocol for network communication.

Mitigation Strategies

Immediate mitigation involves updating the Linux kernel to a version that includes the fix for this vulnerability. Check your distribution's security advisories for kernel updates. If updating is not immediately possible, consider disabling the CAN BCM module if it is not required, using modprobe -r can_bcm.

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