[CVE-2026-72312][MODERATE REGULAR] octeontx2-af: fix VF bringup affecting PF promiscuous state [ Upstream

[CVE-2026-72312][MODERATE REGULAR] octeontx2-af: fix VF bringup affecting PF promiscuous state [ Upstream

[AL-KERNEL]

CVE: CVE-2026-72312
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: octeontx2-af: fix VF bringup affecting PF promiscuous state [ Upstream
Commit: daa2451640a3e0727fd598f5c2ccb8bb4d5a8b9c
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=daa2451640a3e0727fd598f5c2ccb8bb4d5a8b9c
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72312
Analysis date: Sat, 15 Aug 2026 09:37:37 -0400
ActionableScore: 4
ActionableScore lower bound: 3
Actionable bucket: Borderline Actionable Moderate / Manual review recommended
Manual review required: YES

Summary:
A VF rx mode mailbox request in octeontx2-af can incorrectly clear PF promiscuous and allmulti MCAM rules, allowing a VF controlled guest or tenant to disrupt PF receive filtering state in affected SR-IOV deployments.

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

The original Linux kernel CVE announcement for CVE-2026-72312 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72312

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: YES

A detailed explanation of the methodology and priority rules is included
at the end of this message.

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AL-KERNEL CLASSIFICATION RESULT
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CVE-2026-72312	MODERATE	CHECK WITH IMPACT FROM ORIG NN MODERATE	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:A/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:H';CWE-284;CWE-862;CWE-863;Other CVSS 'AV:A/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L';BEST CVSS score: '5.4';DESCR 'A VF rx mode mailbox request in octeontx2-af can disable PF promiscuous and allmulti MCAM rules because the disable helpers operate on PF state even when the request is issued through a VF interface. A VF bringup or teardown with promiscuous and allmulti flags set to false can therefore affect the parent PF receive mode and may disrupt packet visibility or multicast/promiscuous traffic handling on the PF. For the CVSS the PR:L is used because reliable triggering requires control of a VF network interface or an assigned guest or process with enough network administration capability to change VF rx mode. The issue is not directly reachable from the public network by ordinary packets and is better treated as adjacent or device mediated access through SR IOV or similar VF assignment. Impact is mainly integrity and availability of PF network behavior, not kernel memory corruption or privilege escalation.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline Actionable Moderate / Manual review recommended (with actual score 4)	YES	REMOTE SIMPLEFIX NETWORK PACKET  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	YES	NO	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=4
ActionableScoreLower=3

## 1. ActionableScore

* Conservative score: 3
* Paranoid score: 4
* Final recommended bucket: **Borderline Actionable Moderate / Manual review recommended**::

## 2. Signal breakdown

Triggered signals:

* Cross-boundary isolation/policy bypass: +1
  A VF mailbox request can affect PF MCAM promiscuous and allmulti rules, crossing the intended VF to PF control boundary.

* Integrity impact plausible: +1
  The VF can alter PF receive filtering state, which may violate expected network policy or monitoring behavior.

* Availability impact realistic: +1
  Clearing PF promiscuous or allmulti rules can disrupt multicast or promiscuous traffic delivery for PF workloads.

* Practical exploit chain strongly implied: +1
  The commit directly states that VF bringup or teardown with both flags false can clear PF rules.

Subtractions:

* Reduced privilege or delegated admin requirement: -1 in conservative scoring
  Triggering likely requires control of a VF interface, commonly CAP_NET_ADMIN inside a guest or tenant environment. This is not full host root, so a full -2 root penalty is not appropriate.

Not applied:

* No generic memory corruption.
* No UAF, OOB write, double free, refcount issue, or arbitrary write.
* No direct remote packet trigger.
* No confidentiality impact shown.
* No privilege escalation primitive shown.

## 3. Reachability analysis

The likely attacker is a user, guest, or tenant with control over an assigned VF and enough permission to change the VF receive mode or bring the VF interface up or down. In SR-IOV deployments this may be a reduced-privilege administrative context inside a guest rather than full host root.

The issue is not reachable by ordinary network packets from the public Internet. It is device mediated through VF mailbox control operations. Namespaces and containers matter if a VF or network administration capability is delegated to an untrusted workload.

The path is hardware and deployment dependent. It matters mainly on Marvell OcteonTX2 systems using PF/VF separation where PF promiscuous or allmulti mode is security or availability relevant.

## 4. Severity interpretation

This behaves more like an actionable Moderate than an Important-class kernel memory corruption issue. The bug is a PF/VF isolation and network policy correctness issue, not a kernel memory safety bug.

Theoretical impact can be meaningful in multi-tenant SR-IOV deployments because a VF can affect PF packet reception state. Realistic exploitation depends heavily on whether untrusted tenants control VFs and whether the PF relies on promiscuous or allmulti rules for monitoring, bridging, packet capture, or multicast forwarding.

## 5. One-sentence report phrase

A VF rx mode mailbox request in octeontx2-af can incorrectly clear PF promiscuous and allmulti MCAM rules, allowing a VF controlled guest or tenant to disrupt PF receive filtering state in affected SR-IOV deployments.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED

This should not be auto-closed if the product supports OcteonTX2 SR-IOV with untrusted VF tenants, because it is a cross-boundary PF/VF policy bypass. It can be lower priority if all VFs are trusted and PF promiscuous or allmulti mode is not security relevant.

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

Patch: octeontx2-af: fix VF bringup affecting PF promiscuous state [ Upstream
Commit: daa2451640a3e0727fd598f5c2ccb8bb4d5a8b9c
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=daa2451640a3e0727fd598f5c2ccb8bb4d5a8b9c

Changed files:
  drivers/net/ethernet/marvell/octeontx2/af/rvu_nix.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=daa2451640a3e0727fd598f5c2ccb8bb4d5a8b9c

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

The original Linux kernel CVE announcement for CVE-2026-72312 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72312

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:A/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L
  The Best / paranoid CVSS vector: AV:A/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:H
  The Best / paranoid CVSS score: 5.4

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: 3
  Paranoid ActionableScore: 4

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).