[CVE-2026-68096][MODERATE REGULAR] audit: fix recursive locking deadlock in audit_dupe_exe() [ Upstream

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

CVE: CVE-2026-68096
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: audit: fix recursive locking deadlock in audit_dupe_exe() [ Upstream
Commit: 36eb77f14b4e6f2dc1008c1fabe31236397be27a
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=36eb77f14b4e6f2dc1008c1fabe31236397be27a
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68096
Analysis date: Mon, 10 Aug 2026 13:37:26 -0400
ActionableScore: 4
ActionableScore lower bound: 1
Actionable bucket: Borderline, manual review recommended
Manual review required: YES

Summary:
A recursive locking deadlock in the Linux audit executable-rule update path can be triggered during VFS rename handling when fsnotify causes audit rule duplication to re-enter parent path resolution, leading to a local denial of service if matching audit rules are present.

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

The original Linux kernel CVE announcement for CVE-2026-68096 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68096

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: 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-2026-68096	MODERATE	CHECK WITH IMPACT FROM ORIG NN MODERATE	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:H';CWE-667;*CWE-833;CWE-662;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.5';DESCR 'A recursive locking deadlock can occur in the Linux audit subsystem when a rename event triggers fsnotify while the VFS already holds the parent directory inode lock. If an executable audit rule matches the moved file, audit rule duplication can call audit_alloc_mark and re enter path parent resolution for the same directory, causing the task to try to acquire the same I_MUTEX_PARENT lock again. For the CVSS the PR:L is used in the paranoid score because an unprivileged local user may trigger the rename path when a matching audit rule already exists on a user controlled file or directory. The issue is not network reachable and does not indicate a memory corruption primitive. Impact is denial of service through a stuck rename and audit update path, with no supported confidentiality or integrity impact.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline, manual review recommended (with actual score 3)	YES	LOCK DEADLOCK DANGER HARDWARE LINUS  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH	NO	NO	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=4
ActionableScoreLower=1

## 1. ActionableScore

* Conservative score: 1
* Paranoid score: 4
* Final recommended bucket: **Borderline, manual review recommended**

## 2. Signal breakdown

Paranoid score signals:

* Local unprivileged trigger: +1
  If a matching executable audit rule is already installed by policy, a local unprivileged user may trigger the vulnerable rename path by moving a matching user-controlled file.

* Reliable kernel crash / strong DoS: +1
  The commit shows a consistently reproducible recursive locking deadlock in the audit and VFS/fsnotify path.

* Availability impact realistic: +1
  The deadlocked task can remain stuck while holding VFS and audit-related locks, potentially blocking rename operations and audit rule/watch updates beyond a single failed syscall.

* Broad/default/common subsystem exposure: +1
  Audit, VFS rename, and fsnotify are common kernel paths, especially in enterprise distributions, although the exact AUDIT_EXE rule configuration is policy-dependent.

Conservative score signals:

* Reliable kernel crash / strong DoS: +1
  The issue is a demonstrated deadlock.

* Requires admin/root/CAP_AUDIT_CONTROL in typical deployments: -2
  Reliable standalone reproduction requires creating an audit rule with auditctl, normally requiring administrative audit-control privileges.

* Configuration-dependent audit rule exposure: +1 offset / no full rare penalty
  The path is not default for every system, but executable/path audit rules are realistic on hardened or enterprise systems.

No memory corruption, UAF, OOB write, refcount corruption, credential bypass, or file descriptor theft primitive is supported by the patch.

## 3. Reachability analysis

The direct reproducer requires `auditctl`, so a conservative attacker model is local privileged or audit-control capable. However, if an administrator has already installed a matching `AUDIT_EXE` plus path audit rule for a location writable or movable by a normal user, the actual trigger can be just `rename()` or `mv`, which supports the paranoid PR:L interpretation.

This is not network reachable. Namespaces generally do not make audit rule management unprivileged on the host, but container or delegated administration models may change practical exposure if a reduced-privilege service can influence watched paths. The vulnerable path is realistic only when audit executable rules and fsnotify watch updates are active.

Call-site confidence: high, because the patch shows the full call chain from `audit_watch_handle_event()` to `audit_update_watch()`, `audit_dupe_rule()`, `audit_dupe_exe()`, and `audit_alloc_mark()`.

## 4. Severity interpretation

This behaves like a borderline Moderate local DoS issue, not an Important memory-corruption vulnerability. The theoretical impact is a persistent lock deadlock in a security subsystem, but the patch does not show a corruption primitive, stale object reuse, arbitrary write, information disclosure, or privilege escalation path.

The paranoid score is higher because preexisting audit policy can allow a lower-privileged local user to trigger the deadlock without being able to create audit rules. Still, the realistic impact remains availability-only.

## 5. One-sentence report phrase

A recursive locking deadlock in the Linux audit executable-rule update path can be triggered during VFS rename handling when fsnotify causes audit rule duplication to re-enter parent path resolution, leading to a local denial of service if matching audit rules are present.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Reason: availability-only and no memory corruption primitive is visible, but the issue is in the audit security subsystem and may be triggerable by a local unprivileged user when a matching audit policy already exists.

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

Patch: audit: fix recursive locking deadlock in audit_dupe_exe() [ Upstream
Commit: 36eb77f14b4e6f2dc1008c1fabe31236397be27a
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=36eb77f14b4e6f2dc1008c1fabe31236397be27a

Changed files:
  kernel/audit.h
  kernel/audit_fsnotify.c
  kernel/audit_watch.c
  kernel/auditfilter.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=36eb77f14b4e6f2dc1008c1fabe31236397be27a

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

The original Linux kernel CVE announcement for CVE-2026-68096 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68096

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:L/PR:H/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 5.5

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: 1
  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: 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).