CVE-2026-98786 drm/amd/display: guard dc_sink dereferences in MST mode validation
A race condition in the Linux kernel AMD display driver allows a local attacker to cause a denial of service via null pointer dereference during MST unplug.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-98786?
CVE-2026-98786 is a vulnerability in Linux, published on 18 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
drm/amd/display: guard dc_sink dereferences in MST mode validation
dm_dp_mst_is_port_support_mode() reads aconnector->dc_sink->dsc_caps... for the DSC branch-throughput check, and get_conv_frl_bw()'s HDMI-PCON FRL-bandwidth path reads aconnector->dc_sink->edid_caps.max_frl_rate, both without a NULL check. dc_sink is cleared asynchronously on MST unplug, and both functions run from paths that the driver's own comments document as racing that teardown: the connector probe worker's ->mode_valid callback and a compositor's atomic check, neither of which holds the MST manager lock that the teardown path uses. The former does have an existing dsc_aux NULL check, but dsc_aux isn't reliably cleared in every path that clears dc_sink, so it doesn't cover this.
Fail the port-support check and skip the FRL conversion path when the sink is already gone.
(cherry picked from commit 7c3db8da4e039698ae198c870712428644e965c7)
Which versions are affected by CVE-2026-98786?
How do I fix CVE-2026-98786?
Apply the vendor's patch.
Is CVE-2026-98786 being exploited?
There is no known exploitation of CVE-2026-98786 in the wild and no public exploit code.
Sources
Also known as AZL-109053, BELL-CVE-2026-98786, DEBIAN-CVE-2026-98786, GHSA-7r8j-xcf8-cxq6, UBUNTU-CVE-2026-98786.