* [CVE-2026-90085][LOW] octeontx2-af: fix NULL deref in NIX TM tree debugfs read path [ Upstream
@ 2026-09-18 8:16 21% AL-KERNEL
0 siblings, 0 replies; 1+ results
From: AL-KERNEL @ 2026-09-18 8:16 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-90085
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: octeontx2-af: fix NULL deref in NIX TM tree debugfs read path [ Upstream
Commit: fb736d733b0a60377cf53010571c261886446fd5
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fb736d733b0a60377cf53010571c261886446fd5
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90085
Analysis date: Fri, 18 Sep 2026 04:16:07 -0400
ActionableScore: 1
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO
Summary:
A NULL pointer dereference in the octeontx2 af debugfs tm_tree read path can crash the kernel when the SQ context is not initialized, but the issue is local, not network reachable, and shows DoS impact only.
======================================================================
ABOUT THIS REPORT
======================================================================
The original Linux kernel CVE announcement for CVE-2026-90085 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90085
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-2026-90085 LOW https://www.kernelcve.org/list/?q=CVE-2026-90085 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:N/A:H';**CWE-476;CWE-754;CWE-703;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 NULL pointer dereference exists in the octeontx2 af debugfs read path because rvu_dbg_nix_tm_tree_display() can access pfvf sq_ctx before the SQ context has been initialized. A local actor can trigger the issue by reading the nix tm_tree debugfs file for a NIX LF whose transmit queues are not set up, causing a kernel oops or crash. For the CVSS the PR:L is used in the paranoid score when debugfs access is delegated to a less privileged local user, container root, or service account with enough permissions to read the file. In the normal host configuration PR:H is more typical because debugfs access is usually restricted to administrators. The issue is not network reachable and does not involve packet processing. Impact is denial of service only, with no supported evidence of information disclosure or privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1) YES REMOTE WRITE OOB SIMPLEFIX NETWORK DEBUGFS LINUS LOWERED_FROM_HIGH_BASED_ON_GUESSCVSS DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 YES NO checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=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: 1
* Paranoid score: 1
* Final recommended bucket: **Ordinary Moderate**::
No floor or cap changed the score.
## 2. Signal breakdown
Positive signals:
* +1 Reliable kernel crash / strong DoS: reading the `tm_tree` debugfs file when `pfvf->sq_ctx` is NULL can trigger a kernel oops via NULL pointer dereference.
Negative or non-awarded signals:
* +0 Real UAF: not awarded. The patch shows a NULL dereference, not stale post-lifetime object use.
* +0 Strong or weak exploitation leverage: not awarded. No controlled reclaim, arbitrary write, OOB access, callback control, refcount mutation, or object replacement is shown.
* +0 Confidentiality / Integrity: not awarded. There is no disclosure path or unauthorized state modification.
* +0 Remote reachability: not awarded. The trigger is a local debugfs read, not packet processing.
* +0 Local unprivileged trigger: not awarded. Below-host-admin access to this debugfs file is possible only if permissions are delegated or weakened, but that is not established by the patch.
* +0 Extra availability: not awarded. The same oops/crash is already counted once.
## 3. Reachability analysis
The direct trigger is reading `/sys/kernel/debug/octeontx2/nix/tm_tree` for a NIX LF whose transmit queues are not set up. This requires local access to the debugfs file.
`debugfs` is commonly restricted to root or administrator-equivalent users, but the supplied evidence does not show the exact file permissions or deployment policy. Therefore `HostAdminRequired=UNKNOWN`, not `YES`. If the file is readable by a delegated service account, container root, or another less privileged local actor, that actor could trigger the crash, but ordinary unprivileged reachability is not proven.
There is no evidence that the complete trigger is namespace-scoped. No network packet path or remote trigger is established. The affected code is hardware-driver-specific, but the patch does not justify a separate rare-hardware penalty for ActionableScore purposes.
## 4. Primitive and severity interpretation
The primitive is a NULL pointer dereference in `rvu_dbg_nix_tm_tree_display()` because `pfvf->sq_ctx` is used before checking whether the SQ context was allocated.
This is not an active structured UAF, not fixed stale storage, and not a repeated release/refcount case. The demonstrated consequence is kernel oops or crash. The speculative consequence beyond DoS is weak because no memory corruption primitive is established.
PrimitiveClass is `CLASS_C` because the behavior is crash/DoS from invalid state without an independently useful corruption primitive. `ImportantCandidate=NO` because there is no unresolved Class A or strong Class B primitive. `AutoDowngradeAllowed=YES` because this is a constrained NULL-deref debugfs DoS and no meaningful exploitation leverage remains unresolved.
Likely operational severity: ordinary local DoS, usually low priority unless the debugfs file is exposed to less trusted local users.
## 5. One-sentence report phrase
A NULL pointer dereference in the octeontx2 af debugfs tm_tree read path can crash the kernel when the SQ context is not initialized, but the issue is local, not network reachable, and shows DoS impact only.
## 6. Manual review recommendation
NO MANUAL CHECK NEEDED
Reason: the patch establishes only a local debugfs NULL dereference with crash impact and no UAF, refcount mutation, memory corruption, authorization bypass, or remote attack path.
## 7. Call-site confidence
Call-site confidence: high
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: octeontx2-af: fix NULL deref in NIX TM tree debugfs read path [ Upstream
Commit: fb736d733b0a60377cf53010571c261886446fd5
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fb736d733b0a60377cf53010571c261886446fd5
Changed files:
drivers/net/ethernet/marvell/octeontx2/af/rvu_debugfs.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=fb736d733b0a60377cf53010571c261886446fd5
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-90085 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90085
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: unknown
Paranoid ActionableScore: 1
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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