[CVE-2026-98807][MODERATE REGULAR] net/mlx5: Fix slab-out-of-bounds when handling team device events [ Upstream

[CVE-2026-98807][MODERATE REGULAR] net/mlx5: Fix slab-out-of-bounds when handling team device events [ Upstream

[AL-KERNEL]

CVE: CVE-2026-98807
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: net/mlx5: Fix slab-out-of-bounds when handling team device events [ Upstream
Commit: 16ca0e79f31ea810346a79dda545ba344ede1d47
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=16ca0e79f31ea810346a79dda545ba344ede1d47
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98807
Analysis date: Sat, 24 Oct 2026 13:10:04 -0400
ActionableScore: 2
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
mlx5 team events can pass undersized team-port state to bonding helpers, causing a slab out-of-bounds read and potentially incorrect LAG inactive-port handling.

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

The original Linux kernel CVE announcement for CVE-2026-98807 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98807

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 REGULAR
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-2026-98807	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-98807 CHECK WITH IMPACT FROM ORIG NN MODERATE | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=1 LEGACY=MODERATE RESULT=DIFF (final Legacy and Aegis differ; FINAL: MODERATE, Aegis: MODERATE_KPANIC)	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:L';CWE-125;CWE-843;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:L/A:L';BEST CVSS score: '4.4';DESCR 'A slab out of bounds read occurs because mlx5 LAG event handling accepts both bonding and team masters but passes team port private data to bonding specific helpers. The smaller team_port object is then interpreted as a bond slave and bond_is_slave_inactive reads beyond its boundary. The value can affect inactive port tracking and may cause incorrect LAG behavior or limited network availability impact. No out of bounds write, UAF, direct information disclosure path, or supported privilege escalation primitive is shown. For the CVSS the PR:L value in the paranoid vector reflects environments where network administration is delegated to a container or service account, while reliable triggering normally requires CAP_NET_ADMIN and control of mlx5 team configuration. Automated impact decision path. The original SimpleNet classifier selected MODERATE_KPANIC. The primary LLM estimated paranoid CVSS 4.4 and the production ActionableScore returned 2 with recommendation Ordinary Moderate. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were CVSS and initial triage stage MODERATE_KPANIC to MODERATE because the CVSS score, vector or bug class threshold rule was applied. The legacy KP specialist has no review artifact for this run. The legacy FD or DH downgrade specialist has no review artifact for this run. Exact triggered rule markers were DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS and V41_INHERITED_KPANIC_PROMOTION_BLOCKED and MANUAL_REVIEW_REQUIRED. The independent weaker Aegis shadow evaluated CVSS 0.0 and ActionableScore 1 with primitive class CLASS_C and manual review REQUIRED. Its independently reconciled impact was MODERATE_KPANIC. The models disagreed but the aggregation rules retained the production result. The final reported impact is MODERATE.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 2)	MAYBE	REMOTE WRITE KASAN OOB SIMPLEFIX NETWORK HARDWARE LINUS  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS V41_INHERITED_KPANIC_PROMOTION_BLOCKED MANUAL_REVIEW_REQUIRED	-	-	checked

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

ActionableScore=2
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES
RequiresHostUID0=UNKNOWN
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO

1. ActionableScore

* Raw base score: 2.
* Conservative score: 2; no floor or cap applied.
* Raw paranoid score: 2.
* Paranoid score: 2; no technically supported stronger primitive.
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

* +1 weak/indirect corruption concern: a `team_port` is incorrectly interpreted as a larger bonding slave, and `bond_is_slave_inactive()` performs a confirmed slab out-of-bounds read.
* +1 plausible limited availability effect: the out-of-bounds value feeds `has_inactive`, potentially producing incorrect mlx5 LAG inactive-port handling.
* No OOB write, UAF, disclosure path, arbitrary access, controlled payload, protected-state modification, or privilege escalation is shown.
* No reliable kernel crash point: KASAN detection establishes the invalid read, but not a production panic.
* No B5-R retry-accumulated overwrite: the evidence shows neither a write nor retry accumulation.
* No active-state Important candidate: attacker control over the out-of-bounds bytes and a credible less-privileged trust-boundary chain are not established.
* No privilege penalty applied because host-admin-equivalent privilege is not positively proven.

3. Reachability analysis

The trigger requires mlx5 LAG event processing involving a team master and mlx5-backed ports. The supplied summary indicates CAP_NET_ADMIN and control of team configuration are normally needed, but it does not establish which user namespace governs every operation or whether control of the physical mlx5 device can be delegated. Therefore, both host-admin and complete namespace-scoped reachability remain unknown. Applicable Mellanox hardware and team configuration are prerequisites, but no rare-hardware penalty is justified. No race or retry sequence is involved.

4. Primitive and severity reading

The primitive is a read-only slab overrun caused by structural type confusion: bonding helpers consume a smaller `team_port` as though it were a bond slave. The resulting boolean may affect active LAG bookkeeping, but no subsequent unsafe memory write or protected cross-boundary consumer is shown. This is CLASS_C invalid-state/availability behavior, not CLASS_A/B corruption. ImportantCandidate is NO because useful leverage beyond incorrect LAG state is unsupported. Auto-downgrade is allowed, although manual confirmation of capability scope and production behavior is recommended.

5. One-sentence report phrase

mlx5 team events can pass undersized team-port state to bonding helpers, causing a slab out-of-bounds read and potentially incorrect LAG inactive-port handling.

6. Manual review advice

MANUAL CHECK RECOMMENDED

Confirm the complete CAP_NET_ADMIN/device-ownership boundary and whether non-KASAN kernels can suffer a material network outage.

7. Call-site confidence

Call-site confidence: high

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

Patch: net/mlx5: Fix slab-out-of-bounds when handling team device events [ Upstream
Commit: 16ca0e79f31ea810346a79dda545ba344ede1d47
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=16ca0e79f31ea810346a79dda545ba344ede1d47

Changed files:
  drivers/net/ethernet/mellanox/mlx5/core/lag/lag.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=16ca0e79f31ea810346a79dda545ba344ede1d47

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

The original Linux kernel CVE announcement for CVE-2026-98807 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98807

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:L/A:L
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L
  The Best / paranoid CVSS score: 4.4

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: MODERATE
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): MODERATE REGULAR

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).