CVE-2026-68236 in Linux
Summary
by MITRE • 08/10/2026
In the Linux kernel, the following vulnerability has been resolved:
drm/amd/display: set new_stream to NULL after release
In dm_update_crtc_state(), the skip_modeset path releases new_stream via dc_stream_release() but does not set the pointer to NULL.
If a later error (e.g., color management failure) triggers the fail label, the error path calls dc_stream_release() again on the same dangling pointer, causing a double release and potential use-after-free.
Fix this by setting new_stream to NULL after the initial release.
(cherry picked from commit 99f3af19073b3ddbfd96e789124cce12c4277b28)
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 08/10/2026
The vulnerability resides within the AMD display driver subsystem of the Linux kernel, specifically in the drm/amd/display component where the dm_update_crtc_state() function handles display stream state updates. This issue manifests as a classic use-after-free condition that occurs when the skip_modeset code path releases a display stream resource but fails to nullify the pointer reference afterward. The underlying problem stems from improper memory management practices where the dc_stream_release() function is called twice on what should be a single resource, creating a dangerous state that can lead to system instability or potential exploitation.
The technical flaw operates through a specific code execution path where the initial release occurs within the skip_modeset conditional branch, followed by an error handling routine that executes the same dc_stream_release() call on a previously released pointer. This double release scenario creates a use-after-free vulnerability that falls under the common weakness enumeration CWE-415, specifically addressing improper deallocation of resources where the same memory location is freed twice. The vulnerability demonstrates a fundamental flaw in resource management where pointer state is not properly maintained after deallocation operations.
The operational impact of this vulnerability extends beyond simple system crashes to potentially enable privilege escalation or denial-of-service conditions within the graphics subsystem. When the error path executes the second dc_stream_release() call, it operates on a freed memory location that may have been reallocated for other purposes, leading to unpredictable behavior that could be exploited by malicious actors. The vulnerability affects systems running Linux kernels with AMD display drivers and presents a risk to both desktop and server environments where graphics processing is utilized. This condition aligns with ATT&CK technique T1068 which covers local privilege escalation through kernel vulnerabilities.
The mitigation strategy involves implementing proper pointer nullification after resource deallocation, ensuring that the new_stream variable is explicitly set to NULL following the initial dc_stream_release() call. This simple yet critical fix prevents subsequent error handling paths from attempting to release the same memory location twice, thereby eliminating the use-after-free condition. The solution adheres to established security practices for memory management and follows proper defensive programming principles that prevent common resource management errors. The fix represents a straightforward code modification that addresses the root cause without introducing compatibility issues or performance regressions in the display subsystem functionality.