From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-97431][MODERATE 7.0] drm/amd/display: Avoid DPMS-on for phantom stream [ Upstream Date: Thu, 24 Sep 2026 18:38:11 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-97431 X-AL-KERNEL-Priority: MODERATE 7.0 X-AL-KERNEL-Severity: MODERATE 7.0 X-AL-KERNEL-Base-Severity: MODERATE X-AL-KERNEL-KPANIC: YES X-AL-KERNEL-ActionableScore: 4 X-AL-KERNEL-ActionableScore-Lower: unknown X-AL-KERNEL-Commit: f2463fc246d3c39be1371389c52b29418ad673d0 List-Id: CVE: CVE-2026-97431 Priority: MODERATE 7.0 AL-KERNEL base severity: MODERATE KPANIC flag: YES Patch: drm/amd/display: Avoid DPMS-on for phantom stream [ Upstream Commit: f2463fc246d3c39be1371389c52b29418ad673d0 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f2463fc246d3c39be1371389c52b29418ad673d0 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97431 Analysis date: Thu, 24 Sep 2026 18:38:11 -0400 ActionableScore: 4 ActionableScore lower bound: unknown Actionable bucket: Borderline / manual review recommended Manual review required: YES Summary: No one-sentence report phrase was found. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-97431 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97431 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: MODERATE 7.0 Manual review required: YES A detailed explanation of the methodology and priority rules is included at the end of this message. ====================================================================== AL-KERNEL CLASSIFICATION RESULT ====================================================================== CVE-2026-97431 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-97431 CHECK WITH IMPACT FROM ORIG NN MODERATE Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H';**CWE-476;*CWE-664;Other CVSS 'AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '6.5';DESCR 'A NULL pointer dereference in the AMD DisplayPort link test path can occur when both a normal stream and its associated phantom stream are processed for DPMS on. Processing the normal stream may destroy the phantom stream, while the later operation still attempts to process the phantom entry and reaches invalid state. A connected DisplayPort monitor, dock, adapter, or test device may be able to reach this path by initiating a DP link test or retraining event when the affected phantom stream configuration is active. For the CVSS the PR:N value is used because an adjacent DisplayPort device does not need an authenticated user account or privileges on the victim system. The issue is adjacent rather than remotely reachable over an IP network. Base attack complexity is high because the failure depends on AMD display hardware, phantom stream usage, and a specific stream update sequence. Impact is denial of service through a kernel NULL pointer dereference or disruption of the graphics subsystem. There is no concrete evidence of an information disclosure, controlled write, or privilege escalation primitive.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline / manual review recommended (with actual score 4) SKIP CVE-2026-97431 UNKNOWN SKIP No affected files built, so skip this CVE NO - - unknown MAYBE DANGER NULLPTR HARDWARE KPANIC - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=4 PrimitiveClass=CLASS_B RealUAF=YES HostAdminRequired=UNKNOWN NamespaceScopedPrivilege=UNKNOWN ImportantCandidate=NO ManualReview=RECOMMENDED AutoDowngradeAllowed=YES 1. ActionableScore * Raw conservative score: 3 * Conservative score: 4 * Raw paranoid score: 4 * Paranoid score: 4 * Applied conservative FLOOR 4: 3 -> 4 because a cached active stream reference is consumed after the phantom stream is destroyed, while host-admin-equivalent privilege is not established. * Final recommended bucket: **Borderline / manual review recommended**:: 2. Signal breakdown Conservative signals: * +2 Real UAF or equivalent lifetime violation. The phantom stream pointer is cached, the first update destroys that stream, and a later update attempts to consume the cached reference. * +1 Reliable kernel fault. The commit directly identifies a NULL pointer dereference. * No negative points. Rare hardware, host-admin privilege, and difficult timing are not established. Paranoid additional signal: * +1 Device-mediated external influence. A connected DisplayPort sink or test device may initiate the link-test or retraining path, although the complete hardware-to-fault path is not visible. Important non-awarded signals: * Controlled reclaim or attacker-shaped replacement is not demonstrated. * No arbitrary or directed kernel read or write is established. * Structured stale-object leverage is not awarded because the demonstrated terminal behavior is a NULL dereference, with no meaningful post-reuse field consumption shown. * Attacker-influenced lifetime manipulation is not awarded because the attacker is not shown to control phantom-stream destruction or replacement. * No concrete repeated release, put, free, or refcount mutation occurs on the stale reference. * Extra Availability is not awarded because it would double-count the same kernel fault. * Confidentiality, integrity, LPE, and direct IP-network reachability are not established. Repeated-release checks: * First operation may destroy the phantom stream: yes. * Exact cached reference survives: directly implied. * Second operation mutates lifetime or refcount state: no evidence. * Concrete repeated release/refcount +1: not awarded. * Paranoid repeated-refcount leverage +1: not awarded. * FLOOR 5: not applied. 3. Reachability analysis The vulnerable path requires AMD display hardware, an active DisplayPort link, a normal stream with an associated phantom stream, and execution of the DP link-test or retraining path. A connected monitor, dock, adapter, or test device may influence the request, making adjacent device-mediated triggering plausible, but direct remote network reachability is not established. The supplied code does not prove that an ordinary logged-in user, DRM master, compositor, delegated display service, or host administrator can independently perform the complete trigger sequence. It also does not establish that the operation is available through an attacker-created namespace. Therefore HostAdminRequired and NamespaceScopedPrivilege remain UNKNOWN. No timing race is required by the shown logic. The failure follows an ordered sequence in which the normal stream update destroys the phantom stream before the cached phantom entry is processed. 4. Primitive and severity interpretation The primitive is an active structured-object lifetime violation. A phantom stream reference is cached and subsequently consumed after the first update destroys the corresponding stream. This is stronger than a simple validation error and supports CLASS_B and RealUAF=YES, although the visible terminal effect is a NULL pointer dereference rather than controlled access to reclaimed memory. This is not a concrete repeated-release case. The later operation calls the display update path with stale state, but no second free, put, or refcount mutation is shown. The demonstrated consequence is a kernel fault or graphics-subsystem disruption. Privilege escalation, disclosure, controlled replacement, and useful post-free corruption remain speculative. ImportantCandidate=NO because no exploitation leverage beyond the crash-capable stale use is established. AutoDowngradeAllowed=YES because this is presently a constrained crash-oriented CLASS_B issue without controlled reclaim, repeated lifetime mutation, disclosure, authorization bypass, or directed corruption. Operationally it is a borderline Moderate issue that warrants confirmation of the exact phantom-stream destruction semantics and external DisplayPort trigger path. 5. One-sentence report phrase A cached AMD DisplayPort phantom stream may be processed after the corresponding normal stream update destroys it, causing a kernel NULL pointer dereference and denial of service under the affected display configuration. 6. Manual review recommendation MANUAL CHECK RECOMMENDED Confirm whether phantom destruction actually frees the stream object or only invalidates related state, and verify whether a connected DisplayPort device can independently trigger the complete path. 7. Call-site confidence Call-site confidence: medium ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: drm/amd/display: Avoid DPMS-on for phantom stream [ Upstream Commit: f2463fc246d3c39be1371389c52b29418ad673d0 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f2463fc246d3c39be1371389c52b29418ad673d0 Changed files: drivers/gpu/drm/amd/display/dc/link/accessories/link_dp_cts.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=f2463fc246d3c39be1371389c52b29418ad673d0 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-97431 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97431 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:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H The Best / paranoid CVSS vector: AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H The Best / paranoid CVSS score: 6.5 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: 4 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: MODERATE KPANIC detected for this report: YES Published priority for this report (same as in Subject): MODERATE 7.0 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).