* [CVE-2026-98050][MODERATE 7.0] mlxsw: spectrum_ptp: Fix napi_gro_receive() call from GC workqueue context [ Upstream
@ 2026-09-25 15:34 21% AL-KERNEL
0 siblings, 0 replies; 1+ results
From: AL-KERNEL @ 2026-09-25 15:34 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-98050
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: mlxsw: spectrum_ptp: Fix napi_gro_receive() call from GC workqueue context [ Upstream
Commit: 4375b3d1c2898886df1f908160c7004bdd938e73
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4375b3d1c2898886df1f908160c7004bdd938e73
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98050
Analysis date: Fri, 25 Sep 2026 11:34:29 -0400
ActionableScore: 4
ActionableScore lower bound: unknown
Actionable bucket: Borderline / manual review recommended
Manual review required: YES
Summary:
No one-sentence report phrase was found.
======================================================================
ABOUT THIS REPORT
======================================================================
The original Linux kernel CVE announcement for CVE-2026-98050 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98050
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-2026-98050 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-98050 CHECK WITH IMPACT FROM ORIG NN IMPORTANT Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H';CWE-362;CWE-667;CWE-119;Other CVSS 'AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '6.4';DESCR 'A race in the mlxsw Spectrum 1 PTP receive path can call napi_gro_receive from a garbage collection workqueue while the same NAPI instance is being polled by a threaded NAPI kthread on another CPU. Both contexts can concurrently modify the NAPI GRO list, causing list corruption and a kernel BUG or kernel panic. An adjacent network attacker may be able to contribute to triggering the condition by sending PTP event traffic that results in unmatched timestamp entries, but reliable exploitation requires a narrow timing window and a Spectrum 1 device with the affected PTP path enabled. For the CVSS the PR:N because no local account or victim side privileges are required when an attacker can send relevant traffic from the reachable Layer 2 network. The issue is AV:A rather than AV:N because PTP traffic is normally limited to a local or trusted Ethernet segment. Impact is at least denial of service through a kernel crash. In the worst case the concurrent kernel list corruption may have limited confidentiality or integrity impact and should be reviewed manually.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline / manual review recommended (with actual score 4) YES REMOTE DANGER NETWORK SKB KERNEL_PANIC_PLUS_UAF HARDWARE KPANIC PACKET KPANIC LOWERED_FROM_HIGH_BASED_ON_GUESSCVSS YES NO checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=4
PrimitiveClass=CLASS_B
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES
1. ActionableScore
* Raw conservative score: 4
* Conservative score: 4
* Raw paranoid score: 4
* Paranoid score: 4
* Final recommended bucket: **Borderline / manual review recommended**::
2. Signal breakdown
* +1 Concrete constrained kernel list corruption. The PTP GC workqueue and threaded NAPI poll concurrently mutate the same live GRO list. The supplied trace confirms list_add corruption, not merely a warning or invalid protocol state.
* +2 Direct adjacent-network reachability. PTP event traffic reaches the affected mlxsw Spectrum-1 receive and timestamp handling path. The attacker needs Layer 2 or otherwise reachable PTP network access, not local host privileges.
* +1 Reliable kernel crash or strong DoS. The supplied trace demonstrates list corruption followed by kernel BUG, Oops, and kernel panic.
* +0 Race penalty not applied. The bug is a race, but the supplied evidence describes a reproducible condition involving PTP timestamp timeout and concurrent threaded NAPI polling. A race label alone is insufficient for a negative point.
* +0 hardware or niche penalty not applied. Spectrum-1 hardware and the PTP path are limiting deployment conditions, but the supplied evidence does not establish that the attacker needs physical access or host administrative setup to send relevant network traffic.
* +0 Controlled reclaim not demonstrated. The patch does not establish attacker-controlled replacement of GRO list nodes, SKB objects, or NAPI state.
* +0 Arbitrary or directed write not demonstrated. Concurrent list mutation corrupts kernel linked-list state, but the attacker is not shown to select the write target or list pointer values.
* +0 Confidentiality and integrity impact not awarded. The trace establishes corruption and panic, but does not establish information disclosure, persistent data modification, privilege escalation, or controlled non-crash corruption.
* +0 Real UAF not established. No object is shown to be freed and later dereferenced. The failure is concurrent mutation of a still-live GRO list.
* +0 Concrete repeated release or refcount mutation not established. No put, release, free, or refcount operation on a dangling reference is present.
* +0 Strong exploitation leverage not awarded. The active GRO list is corrupted, but the patch does not establish callback control, attacker-shaped replacement contents, controlled list traversal after corruption, or a security-boundary effect.
3. Reachability analysis
The relevant attacker is an adjacent-network attacker able to send PTP-related Ethernet traffic to a host or switch using the affected mlxsw Spectrum-1 PTP receive path. The affected operation is not a local ioctl, netlink control-plane operation, or host configuration interface. Therefore, host administrator privilege is not required for the packet-delivery stage.
The complete vulnerable deployment requires Mellanox Spectrum-1 hardware, the mlxsw driver, threaded NAPI, and the relevant PTP timestamp or trap path to be active. These are deployment prerequisites, but they are not attacker privileges. The supplied context indicates that unmatched PTP timestamp entries can be reproduced during normal PTP state changes such as UNCALIBRATED or SLAVE transitions.
Namespace-scoped privilege is not relevant. The vulnerable NAPI instance belongs to physical Spectrum hardware and the supplied evidence does not establish that an attacker-created network namespace can instantiate the complete mlxsw PTP and threaded NAPI path.
The race requires the garbage-collection workqueue to deliver an unmatched PTP SKB while the owning NAPI polling thread concurrently processes the GRO list on another CPU. This is a synchronization condition, but the supplied trace and reproduction description show that it can occur in ordinary runtime conditions. No hard-race penalty is applied.
4. Primitive and severity interpretation
The exact primitive is concurrent modification of a live NAPI GRO linked list by two execution contexts that are not synchronized with each other. The garbage-collection workqueue calls napi_gro_receive outside the owning NAPI poll context while a threaded NAPI kthread can concurrently execute GRO processing for the same NAPI instance.
This is active kernel list corruption, not fixed stale storage and not a use-after-free. The list nodes and GRO state remain live, but their next and prev links can be modified concurrently and become inconsistent. The demonstrated consequence is list_add corruption followed by a kernel BUG and panic.
The patch does not establish a controlled arbitrary write, controlled object replacement, attacker-controlled callback dispatch, information disclosure, integrity modification, or privilege escalation. The meaningful confirmed impact is adjacent-network-triggerable kernel denial of service on affected PTP-enabled Spectrum-1 deployments.
PrimitiveClass is CLASS_B because a concrete kernel data-structure corruption occurs. ImportantCandidate is NO because the supplied evidence does not establish meaningful attacker control over the corrupted list pointers or a useful post-corruption primitive beyond the crash. AutoDowngradeAllowed is YES because this is currently a constrained crash-capable list-corruption race with no established reclaim, arbitrary write, UAF, authorization bypass, or privilege-escalation mechanism.
5. One-sentence report phrase
A race between mlxsw PTP garbage collection and threaded NAPI GRO processing can corrupt a live GRO list and panic the kernel when adjacent network PTP traffic produces an unmatched timestamp entry.
6. Manual review recommendation
MANUAL CHECK RECOMMENDED
The issue causes concrete concurrent kernel list corruption and a demonstrated panic, but the available patch context does not establish controlled post-corruption writes, object reuse, information disclosure, or privilege escalation.
7. Call-site confidence
Call-site confidence: medium
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: mlxsw: spectrum_ptp: Fix napi_gro_receive() call from GC workqueue context [ Upstream
Commit: 4375b3d1c2898886df1f908160c7004bdd938e73
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4375b3d1c2898886df1f908160c7004bdd938e73
Changed files:
lib/list_debug.c
drivers/net/ethernet/mellanox/mlxsw/spectrum_ptp.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=4375b3d1c2898886df1f908160c7004bdd938e73
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-98050 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98050
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:H/PR:N/UI:N/S:U/C:N/I:N/A:H
The Best / paranoid CVSS vector: AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H
The Best / paranoid CVSS score: 6.4
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: 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: 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).
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