[CVE-2026-53367][LOW] selinux: fix avdcache auditing

[CVE-2026-53367][LOW] selinux: fix avdcache auditing

[AL-KERNEL]

CVE: CVE-2026-53367
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: selinux: fix avdcache auditing
Commit: e3e722ea88e051ae5361dc540c01ba18f87b5ffd
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e3e722ea88e051ae5361dc540c01ba18f87b5ffd
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53367
Analysis date: Sun, 19 Jul 2026 05:58:43 -0400
ActionableScore: 2
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
SELinux per-task avdcache could reuse a stale audited permission mask, causing some locally triggered permission checks to be enforced correctly but omitted from audit logs.

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

The original Linux kernel CVE announcement for CVE-2026-53367 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53367

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-2026-53367	LOW	CHECK WITH IMPACT FROM ORIG NN IMPORTANT	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:L/A:N';CWE-778;CWE-223;CWE-693;BEST CVSS score: '3.3';DESCR 'SELinux per task avdcache could reuse an audited permission mask from an earlier inode permission check instead of recomputing it for the currently requested permissions. A local process could therefore perform a sequence of file or directory operations where a later check is enforced correctly but not audited, for example a directory write after a cached directory search. For the CVSS the PR:L is used because the trigger requires a local task or process to perform filesystem permission checks under an SELinux policy, not remote packet traffic. The issue is not network reachable by itself and does not bypass the allow or deny decision. Impact is limited to audit visibility and log integrity because some security relevant permission checks may be missing from audit records.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 2)  SKIP CVE-2026-53367 UNKNOWN SKIP The Fixes patch not applied yet, so unlikely that actual: dde3a5d0f4dce1d1a6095e6b8eeb59b75d28fb3b YES  NO NO unknown 	MAYBE	SIMPLEFIX IMPROVEONLY LINUS  LOWERED_FROM_HIGH_BASED_ON_GUESSCVSS  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5 DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3	-	-	checked

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

ActionableScore=2

## 1. ActionableScore

* Conservative score: **2**
* Paranoid score: **2**
* Final recommended bucket: **Ordinary Moderate / Low-like**

## 2. Signal breakdown

Triggered signals:

* **Local unprivileged trigger: +1**
  A local process can perform filesystem permission checks that hit the SELinux per-task avdcache.

* **Integrity impact plausible: +1**
  The integrity affected is audit/log integrity: some permission checks may be enforced correctly but not audited.

Not triggered:

* **Remote reachable: +0**
  This is not packet-triggered or remotely reachable by itself.

* **Privilege escalation plausible: +0**
  The patch does not change access decisions and does not show an allow/deny bypass.

* **Generic memory corruption: +0**
  No UAF, OOB, double-free, refcount bug, stale pointer reuse, or object lifetime issue is shown.

* **Reliable kernel crash / strong DoS: +0**
  No crash, panic, WARN-based DoS, or resource exhaustion is described.

* **Security-boundary bypass with sensitive-object access: +0**
  Missing audit records are security-relevant, but the patch does not show access to otherwise protected files, FDs, credentials, or process state.

## 3. Reachability analysis

The bug is reachable by a local task that performs SELinux-mediated inode permission checks. A realistic trigger is a sequence such as a cached directory search followed by a directory write where the later operation should be audited differently.

Namespaces or containers do not materially increase severity unless the deployment relies on SELinux audit logs for tenant monitoring. The issue is SELinux-specific and requires SELinux to be enabled and relevant audit policy to matter. It is not network reachable by itself and does not appear to be default-exploitable as a privilege escalation path.

## 4. Severity interpretation

This behaves like an **ordinary Moderate / Low-like audit correctness issue**, not an Important-class kernel vulnerability.

Theoretical impact is missed security audit visibility. Realistic exploitation evidence supports missing audit records only. There is no demonstrated memory corruption, no access-control bypass, no sensitive FD theft, no credential exposure, and no kernel crash.

## 5. One-sentence report phrase

SELinux per-task avdcache could reuse a stale audited permission mask, causing some locally triggered permission checks to be enforced correctly but omitted from audit logs.

## 6. Manual review recommendation

**NO MANUAL CHECK NEEDED**

This can be auto-closed for urgent security triage because the issue is limited to SELinux audit logging correctness and does not show memory corruption, privilege escalation, remote reachability, or DoS.

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

Patch: selinux: fix avdcache auditing
Commit: e3e722ea88e051ae5361dc540c01ba18f87b5ffd
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e3e722ea88e051ae5361dc540c01ba18f87b5ffd

Commit description:

The per-task avdcache was incorrectly saving and reusing the
audited vector computed by avc_audit_required() rather than
recomputing based on the currently requested permissions and
distinguishing the denied versus allowed cases. As a result,
some permission checks were not being audited, e.g.
directory write checks after a previously cached directory
search check.

Cc: stable@vger.kernel.org
Fixes: dde3a5d ("selinux: move avdcache to per-task security struct")
Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
[PM: line wrap tweaks]
Signed-off-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  security/selinux/hooks.c
  security/selinux/include/objsec.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=e3e722ea88e051ae5361dc540c01ba18f87b5ffd

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

The original Linux kernel CVE announcement for CVE-2026-53367 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53367

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:L/PR:L/UI:N/S:U/C:N/I:L/A:N
  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).