[CVE-2026-90062][LOW] netfilter: nf_tables: move hardware offload step after building the chain blob [ Upstream

[CVE-2026-90062][LOW] netfilter: nf_tables: move hardware offload step after building the chain blob [ Upstream

[AL-KERNEL]

CVE: CVE-2026-90062
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: netfilter: nf_tables: move hardware offload step after building the chain blob [ Upstream
Commit: 923f824f30faebc5560c3061a595063cecdbdbb8
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=923f824f30faebc5560c3061a595063cecdbdbb8
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90062
Analysis date: Thu, 17 Sep 2026 19:56:43 -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-2026-90062 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90062

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-2026-90062	LOW	https://www.kernelcve.org/list/?q=CVE-2026-90062 CHECK WITH IMPACT FROM ORIG NN MODERATE	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L';CWE-863;CWE-670;CWE-693;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:L/A:L';BEST CVSS score: '4.5';DESCR 'nf_tables hardware offload could be committed before the software chain blob for the next ruleset generation was fully prepared. If a later commit preparation step failed, the NIC offloaded ruleset and the kernel software ruleset could temporarily diverge and enforce different packet filtering behavior. This is a control plane logic issue rather than memory corruption. For the CVSS the PR:L is used in the paranoid score because some deployments delegate network administration to a reduced capability root, container root, or service account, although the typical case still requires CAP_NET_ADMIN. The issue is not directly network reachable and cannot be triggered by packet traffic alone. Impact is a possible network policy bypass or filtering inconsistency with limited confidentiality or integrity impact, plus limited availability impact from broken or inconsistent rule enforcement.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 2)	YES	REMOTE INIT SIMPLEFIX NETFILTER HARDWARE PACKET  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3	NO	NO	checked

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

ActionableScore=2
ActionableScoreLower=1
PrimitiveClass=NONE
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES

1. ActionableScore

* Raw conservative score: 1
* Conservative score: 1. No floor or cap applied.
* Raw paranoid score: 2
* Paranoid score: 2. No floor or cap applied.
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

Conservative signals:

* +1. Concrete active policy consistency issue. The patch shows that nftables hardware offload could be committed before software chain blob preparation, creating a state where NIC offloaded rules and software rules differ.
* 0. No RealUAF. No stale lifetime use, refcount misuse, double release, RCU lifetime mismatch, or post-free object access is established.
* 0. No memory corruption primitive. The patch is an ordering and rollback fix in nf_tables commit handling.
* 0. No reliable kernel crash is established.
* 0. No direct remote reachability. Packet traffic alone does not trigger the vulnerable commit path.
* 0. No host-admin penalty applied because host-admin-equivalent privilege is not positively established from the supplied evidence. CAP_NET_ADMIN is expected for nftables updates, but exact namespace and hardware-offload scope is unresolved.
* 0. No local unprivileged bonus because below-host-admin reachability is not positively established.

Paranoid additional signal:

* +1. Limited policy-bypass concern. If commit preparation fails after NIC offload state was changed, packet filtering behavior could temporarily differ between hardware and software paths, plausibly causing limited confidentiality or integrity impact in deployments relying on hardware offload for enforcement.

Important non-awarded signals:

* Controlled reclaim not demonstrated.
* Arbitrary write not demonstrated.
* UAF not demonstrated.
* Authorization ALLOW-vs-DENY bypass not directly established.
* Privileged FD or sensitive resource theft not established.
* Strong semantic reinterpretation not established.
* Remote packet-triggered exploitation not established.
* Extra availability not awarded because no crash, hang, or persistent resource exhaustion is shown.
* Manual-review floor not applied because there is no concrete corruption, lifetime, ownership, COW, or authorization primitive.

3. Reachability analysis

The vulnerable path is the nf_tables control-plane commit path, not packet processing. An attacker would need the ability to submit nftables ruleset changes involving hardware offload. That normally implies CAP_NET_ADMIN or an equivalent network-management role, but the supplied evidence does not prove whether the complete operation requires host/init namespace CAP_NET_ADMIN or can be performed through a delegated namespace-scoped capability.

NamespaceScopedPrivilege is UNKNOWN. The presence of nf_tables and network namespaces is not enough to prove that the full hardware-offload commit path is namespace-scoped, especially because real NIC offload can involve host-owned device state.

Prior setup is likely required in practice: nftables hardware offload must be available and a capable NIC or driver path must be used. This is a configuration prerequisite, but it is not scored as a strong rarity penalty because the patch itself concerns a supported runtime feature and the prompt requires concrete evidence before subtracting for niche deployment.

Race repeatability is not relevant. This is an ordered commit-stage logic issue, not a timing race.

4. Primitive and severity interpretation

The exact issue is a commit-ordering flaw: hardware offload can be applied before the next-generation software chain blob is fully prepared. If later preparation fails, hardware and software packet-filtering state may diverge.

This is not an active structured UAF, not fixed stale storage, and not a cleanup/destructor lifetime bug. There is no concrete repeated release or refcount mutation. There is also no evidence that the bug gives an attacker controlled kernel memory corruption, arbitrary read/write, or privilege escalation.

PrimitiveClass is NONE because the supplied patch establishes a potential enforcement inconsistency, but not a concrete memory-corruption, lifetime, ownership, authorization, or demonstrated security-boundary primitive strong enough for Class A or Class B. It also does not demonstrate a crash-only Class C failure.

ImportantCandidate is NO because the patch supports a low-score local/control-plane policy consistency issue, not an unresolved kernel corruption or strong boundary bypass. AutoDowngradeAllowed is YES because no meaningful unresolved exploitation leverage would be lost by treating this as ordinary Moderate/Low-like triage.

Likely operational severity is low to moderate. Systems relying heavily on nftables hardware offload for strict traffic isolation may still want operational validation, but this does not look like an Important-class kernel vulnerability from the supplied evidence.

5. One-sentence report phrase

nf_tables could commit NIC hardware offload before software chain blob preparation completed, allowing a failed commit path to leave hardware and software rulesets temporarily inconsistent and causing a limited packet filtering policy inconsistency rather than memory corruption or privilege escalation.

6. Manual review recommendation

NO MANUAL CHECK NEEDED

Reason: no UAF, no memory corruption, no direct remote trigger, no demonstrated authorization bypass, and no Important-grade primitive is established.

7. Call-site confidence

Call-site confidence: medium

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

Patch: netfilter: nf_tables: move hardware offload step after building the chain blob [ Upstream
Commit: 923f824f30faebc5560c3061a595063cecdbdbb8
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=923f824f30faebc5560c3061a595063cecdbdbb8

Changed files:
  net/netfilter/nf_tables_api.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=923f824f30faebc5560c3061a595063cecdbdbb8

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

The original Linux kernel CVE announcement for CVE-2026-90062 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90062

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:L/A:L
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L
  The Best / paranoid CVSS score: 4.5

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: 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 alexanjelausa@gmail.com (and both
send reply to CVE record itself too and see "reply" button below for howto reply).