Executive brief
A security vulnerability has been identified in the Linux kernel's CAN Broadcast Manager (BCM) component. This flaw allows a standard user with limited access to execute malicious code with the highest level of system privileges (root). An attacker who successfully exploits this can take full control of the affected system, potentially leading to data theft or complete service disruption.
Technical details
A flaw was discovered in the Linux kernel's Controller Area Network (CAN) Broadcast Manager (BCM) implementation. The vulnerability is classified as an expired pointer dereference (CWE-825) within the bcm_op runtime updates. An unprivileged local attacker can exploit this race condition or improper locking mechanism to trigger arbitrary kernel code execution. While a Proof of Concept (PoC) exists that utilizes unprivileged user namespaces and the kernel-modules-extra package, the underlying vulnerability is reachable without these specific configurations. Successful exploitation results in local privilege escalation (LPE) to root. Fixes involve switching timers to HRTIMER_MODE_SOFT and implementing proper locking for runtime updates.
Affected products
- Red Hat Red Hat Enterprise Linux 8 All versions
Timeline
- 2026-07-27: disclosed: Vulnerability reported and published in NVD/Red Hat Bugzilla