* [CVE-2026-90268][MODERATE 7.0] scsi: sd: Fix error handling in sd_probe() after large pool creation failure [ Upstream
@ 2026-09-17 22:30 21% AL-KERNEL
0 siblings, 0 replies; 1+ results
From: AL-KERNEL @ 2026-09-17 22:30 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-90268
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: scsi: sd: Fix error handling in sd_probe() after large pool creation failure [ Upstream
Commit: 748a14a0d41cfe3017251c11b314f85045414942
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=748a14a0d41cfe3017251c11b314f85045414942
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90268
Analysis date: Thu, 17 Sep 2026 18:30:53 -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.
======================================================================
ABOUT THIS REPORT
======================================================================
The original Linux kernel CVE announcement for CVE-2026-90268 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90268
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.
======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================
CVE-2026-90268 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-90268 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:H/I:H/A:H';*CWE-416;*CWE-672;CWE-404;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7';DESCR 'A lifetime handling error in sd_probe can free sdkp after device_add has already registered the embedded disk_dev object. The registered device and its sysfs entry can then retain references into freed memory, creating a potential use after free if the device model, sysfs, or asynchronous cleanup code accesses the object later. Triggering requires a SCSI device with a sector size larger than PAGE_SIZE and a failure in sd_large_pool_create, so the race free path is local and has high attack complexity. For the CVSS the PR:L value is used for the paranoid score because a reduced capability storage service account, container root, or a user with delegated storage management may be able to initiate device discovery without having unrestricted host administrator privileges. Impact is at least denial of service through a kernel crash and the stale registered object may allow confidentiality and integrity impact if the freed allocation is reused before a later access. The issue is not directly network reachable, although remotely backed SCSI transports such as iSCSI may provide an indirect path when device management and allocation failure conditions are also satisfied.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate / Strong Important candidate requiring manual review (with actual score 5) SKIP CVE-2026-90268 UNKNOWN SKIP The Fixes patch not applied yet, so unlikely that actual: url YES NO NO unknown MAYBE INIT SIMPLEFIX LEAK ERRORPATH HARDWARE KPANIC MEMORY KPANIC INCREASED_TO_HIGH_BASED_ON_GUESSCVSS DECREASED_TO_MODERATE7_BASED_ON_FALSEPOSCHECKOFKP - - checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=5
ActionableScoreLower=4
PrimitiveClass=CLASS_B
RealUAF=YES
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=YES
ManualReview=REQUIRED
AutoDowngradeAllowed=NO
1. ActionableScore
* Raw conservative score: 4
* Conservative score: 4
* Raw paranoid score: 5
* Paranoid score: 5
* No floor or cap changed either score.
* Final recommended bucket: **Actionable Moderate / Strong Important candidate requiring manual review**::
2. Signal breakdown
Conservative signals:
* +2 Real UAF and lifetime violation. `device_add()` publishes the embedded `disk_dev`, but the old error path directly frees its containing `sdkp` while the registered device and sysfs entry remain reachable.
* +1 Reliable kernel crash concern. A later device-model or sysfs operation can dereference the registered object after its containing allocation has been freed.
* +1 Concrete persistent kernel resource or reference leak. The commit explicitly establishes that the sysfs entry remains registered after the failed probe.
* No negative privilege point. Host-admin-equivalent privilege is not positively established by the supplied path.
* No timing penalty. This is an ordered probe error path, not a demonstrated narrow race.
* No rare-hardware penalty. A large-sector SCSI device is required, but the evidence does not establish physical-only or genuinely rare hardware.
Paranoid additional signal:
* +1 Privileged kernel or device-management lifetime corruption path. The stale object remains published in the device model rather than being confined to an immediate cleanup dereference, so later structured device operations remain unresolved.
Not awarded:
* Controlled reclaim or attacker-shaped replacement contents are not demonstrated.
* Arbitrary or directed kernel write is not demonstrated.
* Structured stale-object leverage is not separately awarded because attacker influence over reclaimed contents or consumed fields is not established.
* Weak LPE is not awarded merely because this is a UAF.
* Confidentiality and integrity points are not awarded from theoretical allocator reuse.
* Direct remote reachability is not established. An iSCSI-backed device would still require additional local configuration and allocation-failure conditions.
* No extra Availability point is awarded for the same possible kernel crash.
* No concrete repeated release or refcount operation exists. The patch fixes an incorrect direct `kfree()` after publication, not a second `put()` on the same dangling reference.
* The repeated-release paranoid bonus does not apply.
* REAL UAF FLOOR 5 was not applied. The paranoid score reaches 5 through arithmetic, while below-host-admin reachability and attacker-controlled reuse are not established.
3. Reachability analysis
The path requires probing a SCSI disk whose sector size exceeds `PAGE_SIZE`, followed by failure of `sd_large_pool_create()`. The evidence does not identify who can initiate the complete probe sequence or deliberately produce the allocation failure.
Ordinary unprivileged reachability is therefore not established. Host-admin-equivalent privilege is also not proven as an unavoidable requirement, so `HostAdminRequired` remains `UNKNOWN`. No evidence establishes that the complete operation can be performed with an attacker-obtainable namespace-scoped capability.
A remotely backed transport such as iSCSI could influence device properties, but this is not direct network reachability. Local provisioning, discovery, and memory-allocation failure remain material prerequisites. No race is required, and the failure sequence is deterministic once those prerequisites occur.
4. Primitive and severity interpretation
The primitive is an active structured-object lifetime violation. `sdkp` contains `disk_dev`. After successful `device_add()`, that embedded device is registered and externally represented through the device model and sysfs. The old unwind path then frees `sdkp` without unregistering `disk_dev`, leaving the published object backed by memory outside its valid lifetime.
This is broader than an ordinary cleanup-only stale dereference because the dangling object escapes the failing probe and remains registered. It is not a repeated-release case because no concrete second lifetime or refcount mutation on the same reference is shown.
The patch-supported practical consequence is a persistent stale registration with a plausible kernel fault on later access. Reuse-based corruption, information disclosure, and privilege escalation remain speculative because no controlled reclaim, replacement object, callback use, or directed write is established.
This is CLASS_B rather than CLASS_A. `ImportantCandidate=YES` and `AutoDowngradeAllowed=NO` reflect the unresolved post-free use of an actively published device object. They do not assert that Important-grade exploitation has already been demonstrated. Operationally, this is Actionable Moderate with Important-vs-Moderate review required.
5. One-sentence report phrase
A failed large-sector SCSI disk probe can free an already registered device object while leaving its sysfs representation active, creating a kernel use-after-free with crash potential and unresolved post-free device-model exposure.
6. Manual review recommendation
MANUAL CHECK REQUIRED
Review the complete `out_free_index` path, `scsi_disk_release()` ownership, sysfs callbacks, device reference counts, and whether a below-host-admin actor can repeatedly trigger probing and influence allocation reuse.
7. Call-site confidence
Call-site confidence: medium
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: scsi: sd: Fix error handling in sd_probe() after large pool creation failure [ Upstream
Commit: 748a14a0d41cfe3017251c11b314f85045414942
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=748a14a0d41cfe3017251c11b314f85045414942
Changed files:
drivers/scsi/sd.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=748a14a0d41cfe3017251c11b314f85045414942
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-90268 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90268
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:L/I:L/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 [email protected] (and both
send reply to CVE record itself too and see "reply" button below for howto reply).
^ permalink raw reply [relevance 21%]
Results 1-1 of 1 | reverse | sort options + mbox downloads above
-- links below jump to the message on this page --
2026-09-17 22:30 21% [CVE-2026-90268][MODERATE 7.0] scsi: sd: Fix error handling in sd_probe() after large pool creation failure [ Upstream AL-KERNEL
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox