# CVE-2026-98786: drm/amd/display: guard dc_sink dereferences in MST mode validation

CVE-2026-98786 is fixed in linux on 1 platform by DEBIAN-CVE-2026-98786 (version 7.2.10-1), released October 19, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-98786
- Priority: Routine
- CVSS: 4.0 (Moderate)
- EPSS: 0.0017
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Oct 18, 2026
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-98786

## 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)

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 14 | 7.2.10-1 | [DEBIAN-CVE-2026-98786](https://patchblox.com/security/data/fix/linux/debian-cve-2026-98786.md) | Oct 19, 2026 |

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