NULL pointer dereferences in Linux AMD display driver MST validation
Key facts
- Attack vector
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- Privileges required
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- User interaction
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- Attack complexity
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- Impact type
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- Confidentiality · integrity · availability
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- Fix status
- Partial Red Hat: 6 without a fix
No CVSS vector from any source. Fix status from CNA and Red Hat.
Summary
Linux kernel versions from 6.0 are affected by a flaw in the AMD display driver's MST mode validation. The driver reads a DC sink pointer without a NULL check, while an MST unplug can clear that pointer at the same time. The unguarded reads can dereference a NULL pointer once the sink is gone.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
Description from the CNA
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)
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
Remediation
Fixed Linux kernel versions are 6.18.61, 7.2.10 and 7.3. Red Hat lists no fix available for Red Hat Enterprise Linux 8, 9 and 10 and OpenShift Container Platform 4 and 5, and no fix planned for Red Hat Enterprise Linux 6.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
- Fix · CNA Linux (Linux) Fixed in 6.18.61, 7.2.10, 7.3
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 6 | Affected | No fix planned: Out of support scope |
| Red Hat Enterprise Linux 8 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 9 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 4 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 5 | Affected | No fix yet: Fix deferred |
Not affected: 2 products
- Red Hat Enterprise Linux 7
- Red Hat OpenShift Container Platform 4
Timeline
- 2026-10-18 Threatist record created from CVE-2026-98786
- 2026-10-18 Alias added: GHSA-7r8j-xcf8-cxq6
- 2026-10-19 Fix available: Linux/[email protected] · CNA
- 2026-10-24 Affected versions changed · Red Hat
- 2026-10-24 CVSS score added · Red Hat
- 2026-11-06 Affected versions changed · Red Hat
- 2026-11-06 Fix available: Linux/Linux@5684a6c24c0d7c40ef2c4ccb3e4a64cffe76a791, Linux/[email protected] · CNA
- 2026-11-06 1 new reference · CNA
References
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Sources
- CVE-2026-98786 · CVE Program
- CVE-2026-98786 · NVD
- FIRST EPSS
- GHSA-7r8j-xcf8-cxq6 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-98786 · Red Hat security data · CC BY 4.0
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