[CVE-2026-89605][LOW] ecryptfs: release message context on send failure

[CVE-2026-89605][LOW] ecryptfs: release message context on send failure

[AL-KERNEL]

CVE: CVE-2026-89605
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: ecryptfs: release message context on send failure
Commit: 47ce611cb13f0eefa550d5434c1afcd4217bfc3e
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=47ce611cb13f0eefa550d5434c1afcd4217bfc3e
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89605
Analysis date: Sat, 12 Sep 2026 01:28:15 -0400
ActionableScore: 2
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-89605 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89605

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-2026-89605	LOW	https://www.kernelcve.org/list/?q=CVE-2026-89605 CHECK WITH IMPACT FROM ORIG NN LOW	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-772;CWE-404;**CWE-400;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'eCryptfs can leak a message context when ecryptfs_send_message_locked moves it from the free list to the allocated list and ecryptfs_send_miscdev then fails. The leaked context stays on the allocated list and cannot be reused, so repeated send failures can exhaust the finite message context pool and make later eCryptfs operations fail or stall. For the CVSS the PR:L is used because a local user or local process with access to an eCryptfs mount or login flow may be able to trigger filesystem operations that send requests to the userspace daemon, while reliable triggering also depends on the daemon or miscdev send path failing. The issue is not network reachable. Impact is denial of service through resource exhaustion only, with no supported UAF, OOB access, information disclosure, or privilege escalation primitive.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 2)  SKIP CVE-2026-89605 UNKNOWN SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	LOCK DISK INIT SIMPLEFIX HARDWARE LINUS 	-	-	checked

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

ActionableScore=2
PrimitiveClass=NONE
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES

1. ActionableScore

* Raw conservative score: 2
* Conservative score: 2
* Raw paranoid score: 2
* Paranoid score: 2
* No floor or cap changed the score.
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

Positive signals:

* +1 Concrete persistent kernel resource/reference leak. The message context is moved from the free list to the allocated list, and on ecryptfs_send_miscdev() failure it remains allocated and unavailable for reuse.
* +1 Local below-host-admin reachability in an already configured eCryptfs environment. A local user or process using an eCryptfs mount can plausibly cause filesystem operations that require messages to the userspace daemon.

Non-awarded signals:

* Real UAF not awarded. The context is leaked, not freed and then reused.
* Concrete repeated release/refcount not awarded. There is no first release followed by a second lifetime mutation on the same dangling reference.
* Reliable kernel crash not awarded. The supplied evidence supports exhaustion or failed/stalled eCryptfs operations, not a kernel panic.
* Extra availability not awarded. Resource exhaustion is possible only through repeated send failures and is limited to the finite eCryptfs message context pool.
* C/I impact not awarded. No information disclosure, unauthorized write, credential impact, or policy bypass is established.
* Strong or weak LPE leverage not awarded. No controlled reclaim, arbitrary write, callback control, or security-sensitive object corruption is shown.
* Remote reachability not awarded. This is not network-triggerable from the supplied path.
* Race/timing penalty not applied. This is an ordered error-path leak, not a timing race.

3. Reachability analysis

A local user or local process can plausibly reach the affected path when eCryptfs is in use and filesystem operations require communication with the eCryptfs userspace daemon. Reliable triggering also depends on ecryptfs_send_miscdev() failing, for example because the daemon or miscdev communication path is unavailable or returns an error.

Host-admin-equivalent privilege is not positively required for every trigger in an already deployed eCryptfs environment, so HostAdminRequired=NO. However, initial eCryptfs provisioning or mount setup may involve prior privileged or login-session setup depending on the distribution. Namespace-scoped privilege is UNKNOWN because the patch does not establish that the complete trigger chain is namespace-contained.

No special hardware is required. No direct network exposure is established. No hard race is involved.

4. Primitive and severity interpretation

The exact primitive is a persistent kernel message-context leak on an error path. The object is not freed prematurely and no stale pointer is dereferenced after object lifetime ends. This is therefore not a UAF and not a memory-corruption primitive.

PrimitiveClass=NONE because the established issue is resource leakage only. The demonstrated consequence is local denial of service against eCryptfs operations through depletion of reusable message contexts. Broader host-wide DoS, confidentiality impact, integrity impact, or privilege escalation are not supported by the patch or supplied context.

ImportantCandidate=NO because the issue lacks memory corruption, authorization bypass, ownership violation, or unresolved post-lifetime corruption leverage. AutoDowngradeAllowed=YES because this is a constrained resource leak with no meaningful unresolved exploitation primitive beyond DoS.

5. One-sentence report phrase

eCryptfs may leak message contexts when ecryptfs_send_miscdev() fails after allocation-list insertion, allowing repeated local failures to exhaust the finite context pool and cause eCryptfs operation failures or stalls.

6. Manual review recommendation

NO MANUAL CHECK NEEDED

Reason: this is a resource leak only, with no UAF, OOB access, repeated refcount mutation, authorization bypass, information disclosure, or privilege-escalation primitive.

7. Call-site confidence

Call-site confidence: high

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

Patch: ecryptfs: release message context on send failure
Commit: 47ce611cb13f0eefa550d5434c1afcd4217bfc3e
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=47ce611cb13f0eefa550d5434c1afcd4217bfc3e

Commit description:

ecryptfs_send_message_locked() moves a message context from the free
list to the allocated list before sending the request to the userspace
daemon.

If ecryptfs_send_miscdev() fails, the context is left on the
allocated list and cannot be reused. Move it back to the free list on
failure and clear the caller's pointer.

Fixes: f66e883 ("eCryptfs: integrate eCryptfs device handle into the module.")
Cc: <stable@vger.kernel.org>
Signed-off-by: Yichong Chen <chenyichong@uniontech.com>
Signed-off-by: Tyler Hicks <code@tyhicks.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  fs/ecryptfs/messaging.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=47ce611cb13f0eefa550d5434c1afcd4217bfc3e

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

The original Linux kernel CVE announcement for CVE-2026-89605 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89605

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: 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).