[CVE-2026-74437][MODERATE REGULAR] media: uvcvideo: Fix deadlock if uvc_status_stop is called from async_ctrl.work [ Upstream

[AL-KERNEL <alkernel@kernelcve.org>]

CVE: CVE-2026-74437
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: media: uvcvideo: Fix deadlock if uvc_status_stop is called from async_ctrl.work [ Upstream
Commit: 3659deaf7bf690510899a73906b772740d94342c
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3659deaf7bf690510899a73906b772740d94342c
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74437
Analysis date: Sat, 15 Aug 2026 20:57:49 -0400
ActionableScore: 3
ActionableScore lower bound: 2
Actionable bucket: Ordinary Moderate / Low-like. Not an Important candidate
Manual review required: NO

Summary:
A local UVC device user may trigger a self-deadlock when `uvc_status_stop()` is called from `async_ctrl.work`, causing UVC status or power-management handling to hang without evidence of memory corruption or privilege escalation.

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

The original Linux kernel CVE announcement for CVE-2026-74437 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74437

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 REGULAR
Manual review required: NO

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

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

CVE-2026-74437	MODERATE	CHECK WITH IMPACT FROM ORIG NN MODERATE	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:H';*CWE-833;CWE-667;CWE-662;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'uvcvideo can deadlock when uvc_status_stop is called from async_ctrl.work and then tries to cancel the same work item with cancel_work_sync. This makes the worker wait for itself and can leave UVC status handling or device power management stuck. For the CVSS the PR:L is used for the paranoid score because a local user or local process with access to the video device may be able to trigger the affected UVC control path, while normal driver loading and hardware presence are not enough to make this a remote issue. The issue is not network reachable and requires a local UVC device context, often a camera with asynchronous controls. Impact is denial of service only, with no evidence of memory corruption, information disclosure, or privilege escalation. NO MANUAL CHECK REQUIRED COULD BE AUTOCLOSED';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like. Not an Important candidate (with actual score 3)  SKIP CVE-2026-74437 UNKNOWN SKIP The Fixes patch not applied yet, so unlikely that actual: a32d9c41bdb86e09ce731aa5fd3add89ac2103a5 YES  NO NO unknown 	MAYBE	DEADLOCK USB INIT SIMPLEFIX HARDWARE  DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_GUESSCVSS_AND_CIANNH INCREASED_FROM_LOW_TO_MODERATE70_BASED_ON_ACTIONABLESCOREHIGHEREQTHAN3 DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	-	-	checked

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

ActionableScore=3
ActionableScoreLower=2

## 1. ActionableScore

* Conservative score: 2
* Paranoid score: 3
* Final recommended bucket: **Ordinary Moderate / Low-like. Not an Important candidate**::

## 2. Signal breakdown

Conservative signals:

* Local unprivileged trigger: +1. A local user or local process with access to the UVC video device may be able to exercise the affected asynchronous control path.
* Availability impact realistic: +1. The bug can deadlock UVC status handling or device power management, producing a local DoS for the device or affected workqueue path.

Paranoid additional signal:

* Reliable kernel crash / strong DoS: +1. Not a crash, but in the higher-bound interpretation the self-deadlock may cause a persistent hung task or stuck device-management path requiring device reset or reboot.

Not applied:

* Remote reachable: +0. No network path.
* Firmware-mediated external influence: +0. A device with async controls is required, but this is not a firmware-fed corruption path.
* Generic memory corruption: +0. The patch shows self-deadlock, not UAF, OOB, double-free, or type confusion.
* Privilege escalation plausible: +0. No reclaim, overwrite, callback control, refcount takeover, or credential/security-boundary bypass.
* Confidentiality/Integrity impact: +0. No data disclosure or modification primitive.
* Admin/root penalty: 0. Typical triggering may only require access to the video device, not full host root.

## 3. Reachability analysis

The issue is local and requires a UVC camera with asynchronous controls plus access to the affected UVC control/status path. It is not remotely reachable over the network. Namespaces or containers matter only if the video device is passed through to a less privileged environment. In that case PR remains local user level, but the impact is still limited to DoS. The path is common on desktop or laptop systems with UVC cameras, but the specific async control condition is more specialized than ordinary video capture.

Call-site confidence: high. The commit message provides the exact call chain from `uvc_ctrl_status_event_work()` to `uvc_status_stop()` and the patch directly avoids `cancel_work_sync()` on the currently running work item.

## 4. Severity interpretation

This behaves like an ordinary Moderate or Low-like local DoS. The theoretical impact is a persistent deadlock in UVC status handling or power-management cleanup. Realistic exploitation evidence does not support memory corruption, privilege escalation, information disclosure, or cross-boundary access. It should not be treated as an Important-class kernel vulnerability.

## 5. One-sentence report phrase

A local UVC device user may trigger a self-deadlock when `uvc_status_stop()` is called from `async_ctrl.work`, causing UVC status or power-management handling to hang without evidence of memory corruption or privilege escalation.

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED

The bug is a clearly described self-deadlock with DoS-only impact, no memory corruption primitive, no network reachability, and no plausible privilege-escalation path shown by the patch.

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

Patch: media: uvcvideo: Fix deadlock if uvc_status_stop is called from async_ctrl.work [ Upstream
Commit: 3659deaf7bf690510899a73906b772740d94342c
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3659deaf7bf690510899a73906b772740d94342c

Changed files:
  drivers/media/usb/uvc/uvc_status.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=3659deaf7bf690510899a73906b772740d94342c

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

The original Linux kernel CVE announcement for CVE-2026-74437 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74437

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:L
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 4.7

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: 2
  Paranoid ActionableScore: 3

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: NO
Published priority for this report (same as in Subject): MODERATE REGULAR

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).