CVE-2024-40926 is a vulnerability identified in the Linux kernel's Direct Rendering Manager (DRM) subsystem, specifically within the nouveau driver, which is an open-source driver for NVIDIA graphics cards. The vulnerability arises when the driver attempts to schedule a work item called hpd_work (Hot Plug Detect work) on graphics cards that are headless, meaning they lack display hardware. In such cases, the hpd_work and its associated lock, hpd_lock, remain uninitialized. When the system resumes from runtime power management (PM) states, the driver attempts to schedule this uninitialized hpd_work, leading to a kernel BUG. This BUG is a critical kernel error that can cause system instability or crashes. The root cause is that the nouveau driver does not properly handle headless cards by skipping the scheduling of hpd_work if the card lacks display hardware. The fix implemented involves adding a headless flag to the DRM subsystem and ensuring that any hpd-related operations are skipped if this flag is set, preventing the scheduling of uninitialized work and avoiding the kernel BUG. This vulnerability affects specific Linux kernel versions identified by the commit hash ae1aadb1eb8d3cbc52e42bee71d67bd4a71f9f07, and it was publicly disclosed on July 12, 2024. There are no known exploits in the wild at the time of publication, and no CVSS score has been assigned yet.

For European organizations, the impact of CVE-2024-40926 primarily concerns system stability and availability. Systems running Linux kernels with the affected nouveau driver on headless NVIDIA cards may experience kernel crashes or system reboots when resuming from runtime power management states. This can disrupt critical services, especially in environments relying on Linux servers or workstations with such hardware configurations. Although this vulnerability does not directly lead to privilege escalation or data confidentiality breaches, the resulting denial of service (DoS) due to kernel crashes can affect operational continuity. Organizations using Linux in data centers, cloud infrastructure, or embedded systems with headless GPUs could face unexpected downtime. The lack of known exploits reduces immediate risk, but unpatched systems remain vulnerable to accidental crashes or potential future exploitation if attackers find ways to trigger the condition deliberately.

European organizations should promptly update their Linux kernels to versions that include the patch for CVE-2024-40926. Specifically, they should ensure their distributions have incorporated the fix that adds the headless flag to DRM and prevents scheduling hpd_work on headless cards. For environments where immediate kernel updates are not feasible, administrators should audit systems for the presence of headless NVIDIA cards using the nouveau driver and consider disabling runtime power management features temporarily to avoid triggering the vulnerability during resume operations. Additionally, monitoring kernel logs for BUG messages related to hpd_work scheduling can help detect attempts to exploit or accidental triggers of the vulnerability. Organizations should also coordinate with their Linux distribution vendors to receive timely patches and advisories. In virtualized or containerized environments, verifying the underlying host kernel's patch status is critical since guest systems may be affected indirectly.