CVE-2026-72091 in Linux
Summary
by MITRE • 08/15/2026
In the Linux kernel, the following vulnerability has been resolved:
accel/amdxdna: reject user command submission without a command BO
amdxdna_drm_submit_execbuf() passes the user-supplied command BO handle straight into amdxdna_cmd_submit() with drv_cmd == NULL. When the handle is AMDXDNA_INVALID_BO_HANDLE (0), the block that fetches job->cmd_bo is skipped, leaving it NULL, and no check rejects it on the user path (the !job->cmd_bo guard lives inside the != INVALID branch).
The job is then armed and pushed to the DRM scheduler. aie2_sched_job_run() takes the drv_cmd == NULL path and calls amdxdna_cmd_set_state(job->cmd_bo) -> amdxdna_gem_vmap(NULL) -> to_gobj(NULL)->dev, a NULL pointer dereference in the drm_sched worker. A process with access to the accel node on a system with a probed AMD NPU can trigger a kernel oops with a single AMDXDNA_EXEC_CMD ioctl (cmd_handles = 0).
Only internal driver commands (SYNC_DEBUG_BO / ATTACH_DEBUG_BO) legitimately pass AMDXDNA_INVALID_BO_HANDLE, and they always set drv_cmd. Reject the invalid handle for user submissions (drv_cmd == NULL) at the submit choke point so every user path is covered.
Found by 0sec automated security-research tooling (https://0sec.ai).
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Analysis
by VulDB Data Team • 08/15/2026
The vulnerability exists within the AMD XDNA driver in the Linux kernel, specifically affecting the acceleration subsystem that interfaces with AMD Neural Processing Units. This flaw manifests as a NULL pointer dereference during command submission processing, creating a potential kernel panic condition that can be exploited by unprivileged users with access to the acceleration device node.
The technical implementation reveals a critical logic error in the amdxdna_drm_submit_execbuf() function where user-supplied command buffer object handles are processed without proper validation. When a user submits a command with an invalid handle value of AMDXDNA_INVALID_BO_HANDLE (0), the driver fails to reject this invalid input at the submission boundary. The code path skips the necessary job->cmd_bo initialization when encountering this specific invalid handle, leaving the command buffer object pointer as NULL.
The operational impact becomes evident when the malformed command reaches the DRM scheduler component. The aie2_sched_job_run() function executes with drv_cmd == NULL, leading to a chain of function calls that ultimately results in amdxdna_gem_vmap(NULL) being invoked with a NULL parameter. This NULL pointer dereference occurs within the drm_sched worker context, causing an immediate kernel oops and system instability. The vulnerability is particularly concerning because it requires only a single AMDXDNA_EXEC_CMD ioctl call with cmd_handles = 0 to trigger the condition.
This flaw aligns with CWE-476 which specifically addresses NULL pointer dereferences in software systems. The vulnerability also maps to ATT&CK technique T1068, which covers privilege escalation through local exploitation of kernel vulnerabilities. The issue represents a classic input validation failure where invalid user data bypasses proper sanitization checks at the driver interface boundary.
The recommended mitigation strategy involves implementing explicit validation at the submit choke point within the driver's command submission path. Specifically, the driver should reject any user command submissions that attempt to use AMDXDNA_INVALID_BO_HANDLE when drv_cmd is NULL, effectively blocking all non-internal commands from proceeding with invalid buffer handles. This approach ensures that every user path through the submission logic properly validates input before allowing execution to proceed.
The fix must be implemented at the interface boundary where user commands are first received and validated, preventing the propagation of malformed data into internal driver structures. This defensive programming approach prevents the NULL pointer dereference by ensuring all command buffer objects are properly initialized before being passed to subsequent processing functions. The solution also requires that the existing validation logic for internal driver commands (SYNC_DEBUG_BO and ATTACH_DEBUG_BO) remains intact while extending protection to all user-facing command submissions.
This vulnerability demonstrates the importance of comprehensive input validation in kernel drivers, particularly those handling user-supplied buffer object handles. The flaw highlights how seemingly benign parameter values can lead to catastrophic system failures when not properly validated at appropriate security boundaries, emphasizing the need for robust boundary checking and defensive programming practices in kernel space code where privilege escalation opportunities exist.