[CVE-2026-98774][LOW] rust_binder: cancel deferred work items in thread exit

[CVE-2026-98774][LOW] rust_binder: cancel deferred work items in thread exit

[AL-KERNEL]

CVE: CVE-2026-98774
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: rust_binder: cancel deferred work items in thread exit
Commit: d54df2de22f9ac5b660d0ec898986f805e97c096
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d54df2de22f9ac5b660d0ec898986f805e97c096
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98774
Analysis date: Sat, 24 Oct 2026 04:44:47 -0400
ActionableScore: 2
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
A Binder thread exiting during an active outgoing transaction could leave deferred work uncancelled, retaining transaction state or leaving an IPC participant waiting.

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

The original Linux kernel CVE announcement for CVE-2026-98774 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98774

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.

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

CVE-2026-98774	LOW	https://www.kernelcve.org/list/?q=CVE-2026-98774 CHECK WITH IMPACT FROM ORIG NN LOW | 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:L/PR:L/UI:N/S:U/C:N/I:N/A:L';CWE-404;CWE-459;*CWE-772;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '3.3';DESCR 'rust_binder Thread release previously drained work through get_work_local false, which can skip the thread todo list while process_work_list marks its entries as deferred. If a thread exits during an active outgoing transaction, deferred work may therefore miss its cancel callback and retain Binder transaction state or leave an IPC participant waiting. For the CVSS the PR:L value reflects that triggering requires a local process with Binder access and control of its own Binder thread lifecycle. The required transaction and exit state supports AC:H, while the evidence supports limited local availability impact and does not show UAF, OOB access, information disclosure, arbitrary write, or kernel panic. Automated impact decision path. The original SimpleNet classifier selected LOW. The primary LLM estimated paranoid CVSS 3.3 and the production ActionableScore returned 2 with recommendation Ordinary Moderate. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. No severity changing production threshold or specialist override was recorded. 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. The independent weaker Aegis shadow evaluated CVSS 0.0 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 2)	MAYBE	SIMPLEFIX LINUS 	-	-	checked

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

ActionableScore=2
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES
RequiresHostUID0=NO
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO

1. ActionableScore

* Raw base score: 2.
* Conservative score: 2; no floor or cap applied.
* Raw paranoid score: 2.
* Paranoid score: 2; no stronger primitive is technically supported.
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

* +1 — Local low-privilege trigger: supplied evidence grounds the sequence in a local process with Binder access that controls its own Binder thread exit.
* +1 — Concrete cleanup/resource-retention defect: `Thread::release()` could leave deferred work uncancelled; the fix forcibly enables processing of that list and invokes each work item's `cancel()` callback.
* +0 — A Binder participant may remain waiting, but this is limited availability impact and is not separately counted as reliable kernel crash or strong host-wide DoS.
* No UAF, OOB access, repeated release, arbitrary write, controlled corruption, disclosure, authorization bypass, or protected-resource impact is shown.
* No timing penalty: an active outgoing transaction plus thread exit is conditional, but the evidence does not establish a narrow or uncontrollable race.
* NEW52/B5-R and NEW53/B3-PENDING do not apply: there is no write outside an allocation or shared-backing write.

3. Reachability analysis

The supported actor is a local non-host-admin process with Binder access. No host UID 0, capability, namespace-scoped privilege, special hardware, or prior host-administrator setup is shown as necessary. The actor must arrange an outgoing transaction and exit the Binder thread while work is deferred. Exact repeatability is not demonstrated, but no hard-race penalty is justified.

4. Primitive and severity reading

The primitive is missed cancellation of deferred Binder work during thread teardown, resulting in retained transaction/work state or a waiting IPC participant. It is a CLASS_C cleanup/availability issue, not stale post-lifetime use or memory corruption. The patch does not show that deferred objects are dereferenced after free, repeatedly released, or consumed as corrupted active state. Important-grade leverage is absent, so automatic Moderate handling remains appropriate.

5. One-sentence report phrase

A Binder thread exiting during an active outgoing transaction could leave deferred work uncancelled, retaining transaction state or leaving an IPC participant waiting.

6. Manual review advice

NO MANUAL CHECK NEEDED

The patch supports only a bounded cleanup/resource-retention issue without a corruption or authorization primitive.

7. Call-site confidence

Call-site confidence: medium

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

Patch: rust_binder: cancel deferred work items in thread exit
Commit: d54df2de22f9ac5b660d0ec898986f805e97c096
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d54df2de22f9ac5b660d0ec898986f805e97c096

Commit description:

If there are deferred work items on the thread todo list, then they are
not cleaned up in the Thread::release() method. Thus, update the code to
clean up the work items even if they are deferred.

This can happen if the thread dies while it has an active outgoing
transaction.

Cc: stable <stable@kernel.org>
Fixes: eafedbc ("rust_binder: add Rust Binder driver")
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Link: https://patch.msgid.link/20260903-binder-exit-get-work-v1-1-2d6129a238df@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/android/binder/thread.rs

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=d54df2de22f9ac5b660d0ec898986f805e97c096

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

The original Linux kernel CVE announcement for CVE-2026-98774 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98774

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:L/PR:L/UI:N/S:U/C:N/I:N/A:L
  The Best / paranoid CVSS score: 3.3

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).