* [CVE-2026-93136][LOW] bus: mhi: ep: Fix device refcount leak in the error path of MHI device creation [ Upstream
@ 2026-09-18 8:03 21% AL-KERNEL
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From: AL-KERNEL @ 2026-09-18 8:03 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-93136
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: bus: mhi: ep: Fix device refcount leak in the error path of MHI device creation [ Upstream
Commit: 8acc3813ab5015af73eeb74c9032443162f122d1
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8acc3813ab5015af73eeb74c9032443162f122d1
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93136
Analysis date: Fri, 18 Sep 2026 04:03:44 -0400
ActionableScore: 2
ActionableScore lower bound: 1
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-2026-93136 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93136
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-2026-93136 LOW https://www.kernelcve.org/list/?q=CVE-2026-93136 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-911;*CWE-772;*CWE-401;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'MHI EP device creation can leak device references on the dev_set_name() or device_add() error path after references for the UL and DL channels have already been taken. The leaked references can keep an unregistered device object alive and leave channels associated with a device that was never successfully registered. For the CVSS the PR:L is used in the paranoid score because some deployments may delegate limited device management to a service account or reduced capability root, although typical reliable triggering requires administrator control. The issue is not network reachable and requires local control of the affected MHI endpoint setup plus an error condition during device creation. Impact is denial of service through resource leakage under repeated failures. No UAF or memory corruption primitive is indicated by the patch context.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 2) SKIP CVE-2026-93136 UNKNOWN SKIP The Fixes patch not applied yet, so unlikely that actual: url YES NO NO unknown MAYBE INIT SIMPLEFIX LEAK ERRORPATH HARDWARE LINUS - - checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=2
ActionableScoreLower=1
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES
1. ActionableScore
* Raw conservative score: 1
* Conservative score: 1
* Raw paranoid score: 2
* Paranoid score: 2
* Final recommended bucket: **Ordinary Moderate**::
No floor or cap changed the score.
2. Signal breakdown
Conservative positive signals:
* +1 Concrete persistent kernel resource/reference leak. The patch directly shows that references taken for UL and DL channel ownership are not both released on dev_set_name() or device_add() failure.
Paranoid additional signal:
* +1 Resource accumulation / availability concern. Repeated failures in the MHI EP device creation path could accumulate unreleased device references and associated channel state, creating a plausible resource-exhaustion DoS concern.
Non-awarded signals:
* RealUAF not awarded. The object is kept alive too long by leaked references, not freed too early and then reused.
* Concrete repeated release/refcount not awarded. The vulnerable code drops too few references, not the same reference twice after lifetime may have ended.
* Reliable kernel crash not awarded. The supplied evidence describes a leak and stale association with an unregistered device, not an observed panic or fatal dereference.
* C/I not awarded. No disclosure, unauthorized modification, arbitrary write, object replacement, or privilege-escalation primitive is established.
* Remote reachability not awarded. No network-triggered path is established.
* Host-admin penalty not applied. Host-admin-equivalent triggering is plausible for MHI EP setup, but not fully proven from the supplied context.
* Rare hardware penalty not applied. MHI EP is specialized, but the prompt requires concrete evidence before subtracting for hardware rarity.
Repeated-release/refcount checklist:
* First release can end lifetime: not applicable. The issue is insufficient release.
* Exact same reference survives for a second release: no.
* Second operation is a real lifetime/refcount mutation: no.
* +1 Concrete repeated release/refcount awarded: no.
* Paranoid repeated-refcount leverage awarded: no.
* FLOOR 5 applied: no.
3. Reachability analysis
The vulnerable path is mhi_ep_create_device() in the MHI endpoint bus code. A practical trigger appears to require local control over MHI endpoint device creation or a controller/driver state that causes dev_set_name() or device_add() to fail. The supplied patch does not establish that an ordinary local user can directly invoke the complete path, and it also does not prove that host-admin-equivalent privilege is strictly required. Therefore HostAdminRequired is UNKNOWN.
No namespace-scoped capability path is shown. MHI EP device creation is not a normal network namespace or user namespace operation, so NamespaceScopedPrivilege is NO.
There is no direct packet or network trigger. There may be device/controller prerequisites, but the patch does not provide enough call-site context to score this as physical-only or rare-hardware-only. The issue is not a race. The vulnerable sequence is an ordered error path after references have already been acquired.
4. Primitive and severity interpretation
The exact primitive is a persistent device reference leak in an error unwind path. The UL and DL channel references and the initial device_initialize() reference should be released when device registration fails, but the old code released only one reference.
This is not an active-object UAF. It is not fixed stale storage. It is not a cleanup double-release. It is a missing-release lifetime/resource-management defect where the object remains alive and associated with channels even though it was never registered.
PrimitiveClass is CLASS_C because the demonstrated security behavior is resource leakage and invalid device/channel state, without an independently useful corruption primitive. The demonstrated consequence is resource leakage and possible DoS under repeated failures. A stronger consequence such as memory corruption or privilege escalation is speculative and not supported by the patch.
ImportantCandidate is NO because no UAF, double release, controlled corruption, authorization bypass, COW violation, or meaningful unresolved exploitation primitive is established. AutoDowngradeAllowed is YES because this is a constrained reference/resource leak with no demonstrated security-boundary or corruption leverage.
Likely operational severity is Low to ordinary Moderate. It should be fixed, but it does not appear to need Important-class manual escalation from the supplied evidence.
5. One-sentence report phrase
MHI EP device creation can leak device references on dev_set_name() or device_add() failure, leaving an unregistered device object and channel associations alive and potentially causing resource exhaustion after repeated failures.
6. Manual review recommendation
NO MANUAL CHECK NEEDED
Reason: this is a concrete reference leak with possible resource-exhaustion impact, but no UAF, double release, memory corruption, authorization bypass, remote trigger, or privilege-escalation primitive is established.
7. Call-site confidence
Call-site confidence: medium
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: bus: mhi: ep: Fix device refcount leak in the error path of MHI device creation [ Upstream
Commit: 8acc3813ab5015af73eeb74c9032443162f122d1
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8acc3813ab5015af73eeb74c9032443162f122d1
Changed files:
drivers/bus/mhi/ep/main.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=8acc3813ab5015af73eeb74c9032443162f122d1
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-93136 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-93136
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: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: 1
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 [email protected] (and both
send reply to CVE record itself too and see "reply" button below for howto reply).
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