From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-98692][LOW] thunderbolt: Make the DP tunnel activation callback mandatory Date: Sat, 24 Oct 2026 11:17:41 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-98692 X-AL-KERNEL-Priority: LOW X-AL-KERNEL-Severity: LOW X-AL-KERNEL-Base-Severity: LOW X-AL-KERNEL-KPANIC: NO X-AL-KERNEL-ActionableScore: 1 X-AL-KERNEL-ActionableScore-Lower: unknown X-AL-KERNEL-Commit: 47d60ea801fc333a10c576691eca2e7840b02d3d List-Id: CVE: CVE-2026-98692 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: thunderbolt: Make the DP tunnel activation callback mandatory Commit: 47d60ea801fc333a10c576691eca2e7840b02d3d Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=47d60ea801fc333a10c576691eca2e7840b02d3d Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98692 Analysis date: Sat, 24 Oct 2026 11:17:41 -0400 ActionableScore: 1 ActionableScore lower bound: unknown Actionable bucket: Ordinary Moderate Manual review required: NO Summary: A callback-free DisplayPort tunnel activation leaks a tunnel reference across hibernation restoration, with only limited availability impact demonstrated. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-98692 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98692 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-2026-98692 LOW https://www.kernelcve.org/list/?q=CVE-2026-98692 CHECK WITH IMPACT FROM ORIG NN MODERATE | AEGIS IMPACT LOW AEGIS_AS=1 LEGACY=LOW RESULT=SAME (final reconciliation agrees; DECISION: both LOW) Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L';*CWE-772;*CWE-401;BEST CVSS score: '2.5';DESCR 'A DisplayPort tunnel reference can be leaked because tb_dp_dprx_start takes a reference even when a missing activation callback selects the synchronous path and no dprx_work is queued to release it. The affected path is associated with discovered DP tunnels that are activated again during hibernation restore, so triggering normally requires local control of system power management and a suitable Thunderbolt DisplayPort topology. For the CVSS the PR:L value reflects the local user or service privileges normally needed to request hibernation or otherwise drive the affected lifecycle. The demonstrated primitive is persistent reference retention with low availability impact. There is no supported UAF, out of bounds access, information disclosure, or integrity primitive. Automated impact decision path. The original SimpleNet classifier selected MODERATE. The primary LLM estimated paranoid CVSS 2.5 and the production ActionableScore returned 1 with recommendation Ordinary Moderate. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were CVSS and initial triage stage MODERATE to LOW because the CVSS score, vector or bug class threshold rule was applied. The legacy KP specialist has no review artifact for this run. The legacy FD or DH downgrade specialist has no review artifact for this run. Exact triggered rule markers were DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_GUESSCVSS. The independent weaker Aegis shadow evaluated CVSS 2.5 and ActionableScore 1 with primitive class CLASS_C and manual review REQUIRED. Its independently reconciled impact was LOW. The shadow agreed with the final production impact and aggregation did not change that impact. The final reported impact is LOW.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1) MAYBE READ INIT LEAK LINUS TEST DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_GUESSCVSS - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=1 PrimitiveClass=CLASS_C RealUAF=NO HostAdminRequired=UNKNOWN NamespaceScopedPrivilege=NO ImportantCandidate=NO ManualReview=NO AutoDowngradeAllowed=YES RequiresHostUID0=UNKNOWN AuthorizationDecisionBypass=NO ProtectedResourceImpact=NONE B4PendingReview=NO B4PendingConfirmed=NO 1. ActionableScore * Raw base score: 1. * Conservative score: 1; no floor or cap applied. * Raw paranoid score: 1. * Paranoid score: 1; no additional technically supported consequence. * Final recommended bucket: **Ordinary Moderate**:: 2. Signal breakdown * +1 Concrete persistent kernel reference leak: `tb_dp_dprx_start()` takes a tunnel reference, but the callback-free synchronous path queues no `dprx_work`; neither the worker nor `tb_dp_dprx_stop()` necessarily drops that reference. * +0 Strong DoS: repeated leakage is described, but material host-wide exhaustion or a reliable crash is not shown. * No UAF, OOB access, shared-backing write, authorization bypass, memory corruption, disclosure, or integrity primitive is supported. * NEW52/B5-R does not apply: there is no heap OOB write or corrupted-state consumer. * No privilege, race, rarity, or hardware penalty was applied because the complete trigger restrictions are not established strongly enough for a scored deduction. 3. Reachability analysis The affected path is discovered DisplayPort tunnel activation during hibernation restoration. A suitable Thunderbolt/DisplayPort topology and repeated system power-management lifecycle are implicated. The patch does not establish whether an ordinary user, a delegated power-management service, or only a host administrator can drive the complete sequence; therefore `HostAdminRequired=UNKNOWN` and `RequiresHostUID0=UNKNOWN`. No namespace capability governs this system-wide lifecycle. No difficult timing race is required. 4. Primitive and severity reading The exact primitive is persistent reference retention, not post-lifetime use: the reference keeps the tunnel alive rather than permitting access after free. It is therefore a constrained Class C resource-management/availability issue. The shown effect is leaked tunnel state and removal of a possible hibernation delay; cumulative serious resource exhaustion remains unproven. There is no meaningful Important-vs-Moderate ambiguity, so automatic downgrade is allowed. 5. One-sentence report phrase A callback-free DisplayPort tunnel activation leaks a tunnel reference across hibernation restoration, with only limited availability impact demonstrated. 6. Manual review advice NO MANUAL CHECK NEEDED The patch directly establishes a constrained reference leak without memory corruption, authorization bypass, or a credible unknown cross-boundary primitive. 7. Call-site confidence Call-site confidence: high ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: thunderbolt: Make the DP tunnel activation callback mandatory Commit: 47d60ea801fc333a10c576691eca2e7840b02d3d Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=47d60ea801fc333a10c576691eca2e7840b02d3d Commit description: tb_tunnel_alloc_dp() takes an optional callback which is run from dprx_work once the DPRX capabilities read has completed. Without that callback tb_dp_dprx_start() reads the capabilities synchronously and never queues the work. It however always takes a tunnel reference which is only dropped by dprx_work itself or by tb_dp_dprx_stop() when cancel_delayed_work() actually canceled that work. That reference is thus leaked for every tunnel without a callback. The only tunnels without one are those from tb_tunnel_discover_dp(), which are activated again when restoring from hibernation. Pass the callback to tb_tunnel_discover_dp() as well and drop the synchronous path such that the DPRX capabilities are always read from dprx_work. Hibernation restore then also no longer blocks for up to 12 seconds while waiting for that read to complete. Also fix up the KUnit tests. Fixes: d6d458d ("thunderbolt: Handle DisplayPort tunnel activation asynchronously") Cc: stable@vger.kernel.org Signed-off-by: Sven Peter Signed-off-by: Mika Westerberg Signed-off-by: Greg Kroah-Hartman Changed files: drivers/thunderbolt/tb.c drivers/thunderbolt/test.c drivers/thunderbolt/tunnel.c drivers/thunderbolt/tunnel.h 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=47d60ea801fc333a10c576691eca2e7840b02d3d ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-98692 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98692 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: Not available The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L The Best / paranoid CVSS score: 2.5 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: 1 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).