[CVE-2026-90014][MODERATE 7.0] tracing: Have show_event_filters/triggers files take trace array ref

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

CVE: CVE-2026-90014
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: tracing: Have show_event_filters/triggers files take trace array ref
Commit: 2ee3f7d43f79efaca0cd84a6798653d9d75ce60b
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=2ee3f7d43f79efaca0cd84a6798653d9d75ce60b
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90014
Analysis date: Wed, 16 Sep 2026 12:39:49 -0400
ActionableScore: 5
ActionableScore lower bound: 4
Actionable bucket: Actionable Moderate / Strong Important candidate requiring manual review
Manual review required: YES

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-90014 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90014

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.

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AL-KERNEL CLASSIFICATION RESULT
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CVE-2026-90014	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-90014 CHECK WITH IMPACT FROM ORIG NN IMPORTANT	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H';*CWE-416;CWE-362;*CWE-664;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '7';DESCR 'A use-after-free can occur in the tracing subsystem because show_event_filters and show_event_triggers do not hold a trace_array reference while their seq_file readers iterate events in a tracing instance. A concurrent rmdir of the same tracing instance can free the trace_array while another task is still reading data from it, causing a kernel crash and creating a plausible memory corruption condition. For the CVSS the PR:L is used in the paranoid score because some deployments may delegate tracing or tracefs access to service accounts, reduced capability root, container root, or local users through relaxed permissions. The issue is not network reachable and requires local access to tracing control files. Impact is at least local denial of service via kernel crash and in the worst case may allow confidentiality or integrity impact due to use-after-free memory corruption, so it should be reviewed manually.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate / Strong Important candidate requiring manual review (with actual score 5)  SKIP CVE-2026-90014 UNKNOWN SKIP The Fixes patch not applied yet, so unlikely that actual: url YES  NO NO unknown 	MAYBE	TRACE UAF KERNEL_PANIC_PLUS_UAF LINUS KPANIC  KPANIC DECREASED_TO_MODERATE70_BASED_ON_ACTIONABLESCORELOWERTHAN6	-	-	checked

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

ActionableScore=5
ActionableScoreLower=4
PrimitiveClass=CLASS_B
RealUAF=YES
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=NO
ImportantCandidate=YES
ManualReview=REQUIRED
AutoDowngradeAllowed=NO

1. ActionableScore

* Raw conservative score: 3
* Conservative score: 4
* Raw paranoid score: 4
* Paranoid score: 5
* Conservative floor/cap: Real UAF floor 4 applied, 3 -> 4.
* Paranoid floor/cap: Real UAF floor 5 applied, 4 -> 5.
* Final recommended bucket: **Actionable Moderate / Strong Important candidate requiring manual review**::

2. Signal breakdown

Conservative positive signals:

* +2 Real UAF / lifetime violation: `trace_array` can be freed by `rmdir` while `show_event_filters` or `show_event_triggers` is still open and reading it.
* +1 Reliable kernel crash / strong DoS: commit explicitly says this causes a use-after-free crash.

Conservative negative signals:

* No -2 host-admin penalty: host-admin-equivalent privilege is likely in many tracefs deployments, but the supplied evidence does not positively prove that only host admin can perform the complete read plus rmdir trigger.
* No -1 race penalty: the bug is a race, but the two operations are locally driveable and repeatable by a user that has the relevant tracefs access.
* No rare subsystem penalty: tracing is optional and privileged in practice, but not rare enough by itself for a scoring subtraction.

Paranoid additional signal:

* +1 Attacker-influenced active-object lifetime / repeatable lifetime manipulation: a user with access to tracing instances can plausibly open/read the show files and concurrently remove the same instance, driving both the stale reader and the freeing operation. This is stronger than a fixed stale buffer, because `trace_array` is an active structured object and the read path iterates event state.

Important non-awarded signals:

* Controlled reclaim not demonstrated.
* Arbitrary kernel read/write not demonstrated.
* Callback or function pointer control not demonstrated.
* Concrete repeated release/refcount mutation on the same dangling reference not established.
* Confidentiality and integrity bonuses not awarded, because no concrete disclosure or unauthorized write primitive is shown.
* Extra availability point not awarded, because the crash is already counted once.
* Remote reachability not established.
* Namespace-scoped privilege not established.
* Strong LPE leverage +2 not awarded, because the patch supports UAF and crash, not controlled exploitation.

Repeated-release/refcount checklist:

* First release can end lifetime: not the relevant mechanism here.
* Exact same reference survives for a second lifetime mutation: not established.
* Second operation is a real lifetime/refcount mutation: not established.
* +1 Concrete repeated release/refcount: not awarded.
* Paranoid repeated-refcount leverage +1: not awarded.
* FLOOR 5: applied for paranoid score based on active structured UAF with repeatable lifetime manipulation and nontrivial seq_file iteration, not on repeated refcount mutation.

3. Reachability analysis

The vulnerable path is local tracefs control-plane access. A triggering actor must be able to open/read `show_event_filters` or `show_event_triggers` for a tracing instance and concurrently remove that same instance via `rmdir`.

In default-like deployments, tracing instance management is commonly restricted to root or highly privileged service contexts, but the input does not prove an unconditional host-admin-only capability check for the complete operation. Therefore `HostAdminRequired=UNKNOWN`, not YES.

This is not a network-triggerable bug. It is not known to be namespace-scoped. Tracefs tracing instances are not established here as attacker-created namespace-local resources, so `NamespaceScopedPrivilege=NO`.

Prior host setup may exist in practice if tracefs is mounted or permissions are delegated, but the patch itself is about missing object lifetime protection after the file is opened. No special hardware, boot mode, firmware, or network exposure is required. The race is repeatable by a party that can perform both open/read and rmdir operations.

4. Primitive and severity interpretation

The exact primitive is a real use-after-free of an active structured tracing object. The `trace_array` lifetime is not pinned while seq_file readers iterate event filters or triggers inside that tracing instance. Concurrent instance removal can free the object while the reader still uses it.

This is not fixed stale storage. It is an active structured object, because the stale read path walks tracing instance/event state. It is also not merely a cleanup/destructor-only stale dereference, because the stale use happens in the file read iteration path.

The demonstrated consequence is kernel crash / local DoS. The speculative consequence is broader memory-corruption exploitation from UAF, but no controlled reclaim, arbitrary R/W, disclosure, callback control, or demonstrated LPE is supplied.

Primitive class is CLASS_B. It is a real kernel lifetime/corruption primitive requiring exploitation-leverage review, but it is not CLASS_A because no strong exploitation primitive is established.

`ImportantCandidate=YES` because the bug is an active structured UAF in kernel tracing state and the exploitation leverage is unresolved enough that automatic downgrade would be unsafe. `AutoDowngradeAllowed=NO` because a concrete UAF with meaningful active-object lifetime ambiguity remains, even though Important severity is not independently proven.

Likely operational severity is Actionable Moderate. It should be manually reviewed as a possible Important candidate, especially in products that delegate tracefs access to non-root service accounts, containers, or debugging users.

5. One-sentence report phrase

A local use-after-free in tracing can occur when show_event_filters or show_event_triggers reads a trace_array while a concurrent rmdir frees the same tracing instance, causing a kernel crash and requiring manual review due to active structured object lifetime exposure.

6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: the patch establishes a real UAF of an active structured kernel object, and although only crash is demonstrated, the stale seq_file traversal of freed tracing state leaves enough unresolved exploitation leverage to avoid automatic closure.

7. Call-site confidence

Call-site confidence: high

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

Patch: tracing: Have show_event_filters/triggers files take trace array ref
Commit: 2ee3f7d43f79efaca0cd84a6798653d9d75ce60b
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=2ee3f7d43f79efaca0cd84a6798653d9d75ce60b

Commit description:

The newly added files show_event_filters and show_event_triggers that show
all filters or triggers that are set within the trace array do not take a
reference for the trace array it is showing. Without taking a reference,
the trace_array may be freed via "rmdir" while a task is reading one of
theses files. Those files iterate all the events within an instance
(trace_array) and nothing prevents that instance from being freed while
its data is being read. This causes a use-after-free crash.

Have the open of both those files take the trace_array reference via the
trace_array_get() that prevents the trace_array from being freed while the
files are opened.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260828094153.17b95037@gandalf.local.home
Fixes: 729757b ("tracing: Add show_event_filters to expose active event filters")
Fixes: 6a80838 ("tracing: Add show_event_triggers to expose active event triggers")
Reported-by: Farhad Alemi <farhad.alemi@berkeley.edu>
Closes: https://lore.kernel.org/all/CA+0ovCjerKZJLwXScM9bF2ga2rLi4_XOpUfK41NDbENpeu98jA@mail.gmail.com/
Reviewed-by: Aaron Tomlin <atomlin@atomlin.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  kernel/trace/trace_events.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=2ee3f7d43f79efaca0cd84a6798653d9d75ce60b

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

The original Linux kernel CVE announcement for CVE-2026-90014 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90014

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:H/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 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: 4
  Paranoid ActionableScore: 5

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).