CVE-2026-31488

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

drm/amd/display: Do not skip unrelated mode changes in DSC validation

Starting with commit 17ce8a6907f7 ("drm/amd/display: Add dsc pre-validation in

atomic check"), amdgpu resets the CRTC state mode_changed flag to false when

recomputing the DSC configuration results in no timing change for a particular

stream.

However, this is incorrect in scenarios where a change in MST/DSC configuration

happens in the same KMS commit as another (unrelated) mode change. For example,

the integrated panel of a laptop may be configured differently (e.g., HDR

enabled/disabled) depending on whether external screens are attached. In this

case, plugging in external DP-MST screens may result in the mode_changed flag

being dropped incorrectly for the integrated panel if its DSC configuration

did not change during precomputation in pre_validate_dsc().

At this point, however, dm_update_crtc_state() has already created new streams

for CRTCs

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References