CVE-2026-80703 in Linux
Summary
by MITRE • 08/28/2026
In the Linux kernel, the following vulnerability has been resolved:
drm/amdkfd: Fix missing authorization check in KFD_IOC_DBG_TRAP_DISABLE
Prevent unauthorized termination of active GPU debug sessions. Previously, users with /dev/kfd access could terminate another process's debug session without proper ownership or ptrace authorization.
(cherry picked from commit 4db4c5ffd5585b72622ecf6ffedf2da258ee23f5)
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Analysis
by VulDB Data Team • 08/28/2026
The Linux kernel driver for AMD Kernel Fusion Driver, specifically within the Direct Rendering Manager subsystem, contained a critical authorization bypass vulnerability in the KFD_IOC_DBG_TRAP_DISABLE ioctl handler. This flaw allowed any user with access to the /dev/kfd device node to terminate active GPU debug sessions belonging to other processes without verifying ownership or obtaining necessary ptrace permissions. In Linux systems, the ability to attach to and control another process is strictly governed by security mechanisms such as ptrace restrictions and file descriptor ownership checks. The absence of these validations in this specific kernel interface created a significant gap in access control enforcement for GPU debugging resources.
From a technical perspective, the vulnerability stems from missing validation logic within the ioctl implementation that handles trap disabling requests. When a user initiates a request to disable debug traps on the GPU, the kernel fails to confirm whether the requesting process is the actual owner of the target session or holds valid ptrace authorization over it. This oversight means that any local user can interact with the device file and issue commands that affect processes they do not own. The lack of checks for credentials such as real UID, effective UID, or supplementary group memberships against the target process's security context allows for unauthorized interference with running applications.
The operational impact of this vulnerability is substantial, particularly in multi-user environments where privilege escalation risks are heightened. An attacker could disrupt legitimate debugging sessions, causing application crashes or data corruption by forcibly disabling hardware debug traps. More critically, this flaw can be leveraged to bypass existing security controls that rely on the integrity of GPU-based monitoring or secure execution contexts. By terminating a debug session prematurely, an adversary might evade detection mechanisms tied to those sessions or interfere with forensic analysis efforts. In worst-case scenarios, if combined with other kernel vulnerabilities, this could facilitate further privilege escalation by destabilizing system state or interfering with security modules that depend on accurate process tracking via GPU interactions.
This issue aligns closely with CWE-284, which describes Improper Access Control, as the system failed to restrict actions based on user identity and permissions. It also relates to CWE-732, concerning Incorrect Permission Assignment for Critical Resource, since the device node was accessible without sufficient verification of intent or authority over the targeted resource. From an ATT&CK perspective, this vulnerability supports techniques associated with Defense Evasion, specifically those involving process manipulation or interference with security tools that monitor system behavior through debug interfaces.
To mitigate this risk, it is essential to apply the kernel patch that restores proper authorization checks within the KFD_IOC_DBG_TRAP_DISABLE handler. System administrators should ensure their Linux distributions are updated to include commits that enforce ownership verification and ptrace permission validation before allowing any modifications to GPU debug states. Additionally, restricting access to /dev/kfd through appropriate file system permissions can reduce the attack surface for local users who might attempt to exploit this flaw until patches are fully deployed across all affected systems.