[CVE-2026-89773][LOW] drm/amd/display: Skip Update HDCP Config In Transition State [ Upstream

[CVE-2026-89773][LOW] drm/amd/display: Skip Update HDCP Config In Transition State [ Upstream

[AL-KERNEL]

CVE: CVE-2026-89773
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: drm/amd/display: Skip Update HDCP Config In Transition State [ Upstream
Commit: f733276ae737e4d599d1e19de6722aee1521a154
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f733276ae737e4d599d1e19de6722aee1521a154
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89773
Analysis date: Sat, 12 Sep 2026 01:28:16 -0400
ActionableScore: 2
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
No one-sentence report phrase was found.

======================================================================
ABOUT THIS REPORT
======================================================================

The original Linux kernel CVE announcement for CVE-2026-89773 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89773

The original announcement does not normally provide a security severity
estimate, CVSS assessment, or enough information to determine whether the
reported kernel bug represents a practically relevant security issue.

This report was generated by AL-KERNEL, an AI-assisted Linux kernel
vulnerability analysis system developed by Alexander Larkin. It combines
an autonomous classifier with LLM-assisted technical analysis and a
separate ActionableScore mechanism.

The purpose of this report is to prioritize Linux kernel CVEs before
manual review, identify cases that require prompt investigation, and
support automatic closure of issues that are unlikely to have meaningful
security impact.

Published priority for this report: LOW
Manual review required: NO

A detailed explanation of the methodology and priority rules is included
at the end of this message.

======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================

CVE-2026-89773	LOW	https://www.kernelcve.org/list/?q=CVE-2026-89773 CHECK WITH IMPACT FROM ORIG NN LOW	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H';**CWE-476;CWE-754;CWE-703;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.5';DESCR 'A NULL pointer dereference in the AMDGPU display HDCP update path can occur because update_config may be called during a transition state where config dm_stream_ctx is not valid or dc_sink is missing. The vulnerable path dereferences the connector and sink while preparing HDCP link and display state, which can crash or destabilize the kernel display driver. For the CVSS the PR:L is used because a local user or local display service able to trigger DRM display transitions or HDCP configuration is needed. The issue is not network reachable and is tied to local graphics/display state changes rather than remote packet processing. Impact is denial of service via kernel oops, display stack failure, or possible kernel crash. No concrete information leak, arbitrary write, or privilege escalation primitive is indicated by the code change.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 2)  SKIP CVE-2026-89773 UNKNOWN SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	HARDWARE  INCREASED_FROM_LOW_BASED_ON_HIGHCVSSSCORE DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3	-	-	checked

======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================

ActionableScore=2
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES

1. ActionableScore

* Raw conservative score: 2
* Conservative score: 2
* Raw paranoid score: 2
* Paranoid score: 2
* Final recommended bucket: **Ordinary Moderate**::

No floor or cap changed the score.

2. Signal breakdown

Positive signals:

* +1 Reliable kernel crash / strong DoS: the patch prevents NULL pointer dereferences of `config->dm_stream_ctx`, `aconnector->dc_link`, and `dc_sink` in the AMDGPU HDCP update path.
* +1 Local below-host-admin display reachability: the affected path is tied to DRM display transition and HDCP configuration state, which is plausibly reachable through a local authorized graphics/display stack such as DRM master, compositor, or display service, not direct host administration.

Non-awarded signals:

* +0 RealUAF: no use-after-free or stale post-lifetime object use is established.
* +0 Controlled reclaim: not demonstrated.
* +0 Arbitrary or directed write: not demonstrated.
* +0 Confidentiality and integrity: no disclosure, write primitive, ownership violation, or authorization bypass is established.
* +0 Remote reachability: not network reachable.
* +0 Extra availability: not awarded because the same NULL dereference crash is already counted once.
* +0 Strong LPE or weak LPE concern: not awarded because this is a NULL dereference / invalid transition-state handling issue without a concrete exploitation primitive beyond DoS.
* No negative privilege penalty: host-admin-equivalent privilege is not positively established, and the likely trigger is local display-control activity rather than host root.

3. Reachability analysis

The likely attacker or trigger source is local display activity that causes AMDGPU display transition states while HDCP configuration is updated. Relevant actors include an ordinary logged-in graphical session, a compositor, a display manager, or another authorized DRM master/display-control service. The supplied evidence does not show a raw unprivileged syscall path for every local user, but it supports below-host-admin local reachability through the normal graphics stack.

Host administrator privilege is not positively required. Namespace-scoped privilege is not relevant. No prior privileged setup beyond having AMDGPU display and HDCP-capable paths in use is established. No network trigger is present. No special rare hardware penalty is applied because AMDGPU display hardware is common enough and the issue is not limited to an exotic device class. No race penalty is applied because the issue is an invalid transition-state NULL dereference, not a demonstrated hard timing race.

4. Primitive and severity interpretation

The exact primitive is an invalid NULL pointer dereference in `update_config()` when HDCP configuration is attempted during a transition state without a valid `dm_stream_ctx`, `dc_link`, or `dc_sink`. This is not an active structured UAF and not fixed stale storage. It is a Class C crash/DoS primitive.

There is no concrete repeated release/refcount operation. There is no first lifetime operation that may free an object followed by a second lifetime mutation through the same dangling reference. The demonstrated consequence is display driver failure, kernel oops, or possible kernel crash. The speculative consequence of privilege escalation is not supported by the patch mechanics.

ImportantCandidate=NO because the bug is a NULL dereference without memory corruption, lifetime corruption, authorization bypass, controlled overwrite, COW/ownership violation, or meaningful unresolved exploitation leverage. AutoDowngradeAllowed=YES because the established behavior is constrained DoS and no Important-preserving primitive would be lost by ordinary Moderate handling.

Likely operational severity is ordinary Moderate / local DoS for affected AMDGPU display configurations.

5. One-sentence report phrase

A NULL pointer dereference in the AMDGPU HDCP update path can occur during display transition state when `dm_stream_ctx`, `dc_link`, or `dc_sink` is missing, allowing a local authorized graphics/display context to crash or destabilize the kernel display driver.

6. Manual review recommendation

NO MANUAL CHECK NEEDED

Reason: this is a NULL pointer dereference DoS with no UAF, no memory corruption primitive, no authorization bypass, no network reachability, and no evidence of privilege escalation.

7. Call-site confidence

Call-site confidence: medium

======================================================================
UPSTREAM PATCH SUMMARY
======================================================================

Patch: drm/amd/display: Skip Update HDCP Config In Transition State [ Upstream
Commit: f733276ae737e4d599d1e19de6722aee1521a154
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f733276ae737e4d599d1e19de6722aee1521a154

Changed files:
  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_hdcp.c

Diff excerpt:

Not included in this email. See the upstream URL for the full patch.

Full patch:
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f733276ae737e4d599d1e19de6722aee1521a154

======================================================================
DETAILED REPORT METHODOLOGY
======================================================================

The original Linux kernel CVE announcement for CVE-2026-89773 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89773

The original CVE announcement normally does not include a security-level
estimate. In particular, it may not contain a CVSS assessment, an impact
level, or enough information to determine whether the reported bug is a
practically relevant security issue. One purpose of this parallel CVE list
is to provide that missing technical and prioritization information.

The original goal of the AL-KERNEL project was to prioritize Linux kernel
CVE analysis automatically before manual review. The system can also help
identify non-security issues that may be suitable for automatic closure.

This report was generated by AL-KERNEL, an AI-assisted Linux kernel
vulnerability analysis system developed by Alexander Larkin.

The first analysis stage combines an autonomous classifier with additional
LLM-based analysis. The autonomous classifier runs locally on a CPU and is
based on a backpropagation neural network. Together, these mechanisms
produce a technical vulnerability description, identify likely weakness
types, estimate CVSS severity, and provide input for ActionableScore.

Two CVSS estimates are retained because incomplete kernel vulnerability
information often permits more than one defensible interpretation:

  Conservative CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 5.5

The conservative vector represents a lower-impact interpretation.
The Best/paranoid vector intentionally represents a plausible upper-bound
interpretation and should not automatically be treated as demonstrated
real-world impact.

CVSS may also need to be adjusted for a particular Linux deployment,
because actual reachability, privileges, enabled kernel configuration,
hardware, namespaces, exposed device nodes, and other environmental
conditions can differ significantly between systems.

A separate ActionableScore mechanism evaluates practical remediation
urgency. Its analysis may include reachability, attack prerequisites,
subsystem exposure, memory-corruption characteristics, denial-of-service
reliability, and possible confidentiality, integrity, or
privilege-escalation impact.

  Conservative ActionableScore: unknown
  Paranoid ActionableScore: 2

The final base severity is taken directly from the second tab-separated
field of the AL-KERNEL classification result. ActionableScore does not
replace or independently override that final AL-KERNEL decision, and
if ActionableScore adjusted impact level of ALKERNEL, then you would see
self-readable flags above like INCREASED_TO_HIGH_BASED_ON_ACTIONABLESCOREHIGHEREQTHAN7.

For an AL-KERNEL result of MODERATE, this report uses the following
additional presentation split:

  ActionableScore below 5   -> MODERATE REGULAR
  ActionableScore 5 or more -> MODERATE 7.0

The distinction between MODERATE REGULAR and MODERATE 7.0 makes it
possible to identify Moderate issues that should receive manual analysis
and fixes before lower-priority MODERATE REGULAR issues. In many cases,
MODERATE REGULAR fixes may wait for a later rebase or routine update.

There is one override in which MODERATE REGULAR becomes MODERATE 7.0
even when the ActionableScore is below 5. When the AL-KERNEL result
contains the KPANIC flag, a MODERATE result is always presented as
MODERATE 7.0. The KPANIC flag selected with few regexps without
usage of AI at all, so it helps to detect cases when Kernel Crash happens
and similar (to filter False-Negative results from the LLM usage).

KPANIC indicates that a reliable kernel crash, kernel panic, or similarly
serious kernel availability impact was identified by the classification
workflow.

AL-KERNEL base severity for this report: LOW
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): LOW

These results are intended to support engineering triage. They are
machine-generated estimates, and cases marked for manual review should
be validated by a human security engineer before final disposition.
For more info read docs linked from here: https://kernelcve.org/
(and you can submit you own patch there to generate such a report
for non-existant CVE-id yet).

Note that in many cases this AI tool selects higher severity, than
real is (means you can expect Importants instead of Moderate 7.0 or
Moderates 7.0 instead of regular Moderates). If you see such cases,
please use reply email interface to add additional manual analyses
info to this particular CVE.
And please, please, let me know when you see Lows instead of Importants
or Important instead of Low (because particular for such cases I
need to tune this AI tool to make it better for this one and next similar).
My contact email for such notifications is alexanjelausa@gmail.com (and both
send reply to CVE record itself too and see "reply" button below for howto reply).