CVE-2026-68387 in Linux
Summary
by MITRE • 08/10/2026
In the Linux kernel, the following vulnerability has been resolved:
can: raw: add locking for raw flags bitfield
With commit 890e5198a6e5 ("can: raw: use bitfields to store flags in struct raw_sock") the formerly separate integer values have been integrated into a single bitfield. This led to a read-modify-write operation when changing a flag in raw_setsockopt() which now needs a locking to prevent concurrent access.
Instead of adding a lock/unlock hell in each of the flag manipulations this patch introduces a wrapper for a new raw_setsockopt_locked() function analogue to the isotp_setsockopt[_locked]() approach in net/can/isotp.c
[mkl: use Closes tag instead of Link]
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Analysis
by VulDB Data Team • 08/10/2026
The vulnerability in question involves a concurrency issue within the Linux kernel's CAN (Controller Area Network) subsystem, specifically affecting the raw socket implementation. This flaw emerged from a code refactoring that consolidated multiple integer flag values into a single bitfield structure through commit 890e5198a6e5. The change was intended to optimize memory usage and code organization by using bitfields to store flags within the struct raw_sock data structure, but it inadvertently introduced a race condition during flag manipulation operations.
The technical implementation of this vulnerability stems from the read-modify-write nature of bitfield operations when modifying individual flags through the raw_setsockopt() function. When multiple threads or processes attempt to modify different flags within the same bitfield simultaneously, there is no synchronization mechanism to prevent concurrent access patterns that could result in data corruption or inconsistent flag states. This particular issue falls under the category of race conditions and memory consistency problems as defined by CWE-362, which specifically addresses concurrent execution issues where operations are not properly synchronized.
The operational impact of this vulnerability is significant within automotive and industrial control systems that rely on CAN bus communications, as it could lead to unpredictable behavior in network protocols, corrupted socket configurations, or potential denial of service conditions. The vulnerability affects systems using raw CAN sockets where multiple concurrent operations might be modifying different flags within the same bitfield structure. This type of issue can be particularly dangerous in real-time embedded systems where timing and consistency are critical for proper operation.
The mitigation strategy implemented in this patch follows established kernel development patterns by introducing a dedicated locking mechanism similar to approaches already used elsewhere in the CAN subsystem, specifically referencing the isotp_setsockopt_locked() implementation pattern found in net/can/isotp.c. This solution creates a wrapper function called raw_setsockopt_locked() that encapsulates all flag manipulation operations within appropriate mutex locks, preventing the race conditions while maintaining code clarity and avoiding the complex lock/unlock management patterns that could introduce additional vulnerabilities.
This vulnerability demonstrates the importance of considering concurrency implications during code refactoring, particularly when transitioning from separate variables to bitfield structures. The fix exemplifies proper kernel security practices by addressing the root cause rather than adding superficial protections, and aligns with ATT&CK framework concept T1499.004 which covers network denial of service through resource exhaustion or corruption, as corrupted socket state could potentially lead to communication failures within embedded systems. The solution maintains system stability while ensuring proper synchronization of concurrent access patterns in kernel space operations that handle critical communication protocols used in automotive and industrial environments.