* [CVE-2026-98562][IMPORTANT] net: libwx: fix races in Tx timestamp handling [ Upstream
@ 2026-10-24 7:24 21% AL-KERNEL
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From: AL-KERNEL @ 2026-10-24 7:24 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-98562
Priority: IMPORTANT
AL-KERNEL base severity: IMPORTANT
KPANIC flag: NO
Patch: net: libwx: fix races in Tx timestamp handling [ Upstream
Commit: e78b95cfd5df25d0c562aaef95d3c7fe6c7e0e66
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e78b95cfd5df25d0c562aaef95d3c7fe6c7e0e66
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98562
Analysis date: Sat, 24 Oct 2026 03:24:35 -0400
ActionableScore: 5
ActionableScore lower bound: 4
Actionable bucket: Actionable Moderate / Strong Important candidate requiring manual review
Manual review required: YES
Summary:
A cleanup/worker race can feed a freed Tx-timestamp skb into `skb_tstamp_tx()` and then release the same reference again, creating an active-skb UAF and double-release primitive.
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ABOUT THIS REPORT
======================================================================
The original Linux kernel CVE announcement for CVE-2026-98562 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98562
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: IMPORTANT
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-2026-98562 IMPORTANT https://www.kernelcve.org/list/?q=CVE-2026-98562 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT IMPORTANT AEGIS_AS=6 LEGACY=IMPORTANT RESULT=SAME INDEPENDENT_LEGACY=MODERATE_KPANIC INDEPENDENT_RESULT=DIFF TEMP_KPANIC_MERGE=IMPORTANT_HARD_VETO PRE_MERGE_LEGACY=MODERATE_KPANIC (final reconciliation agrees; DECISION: both IMPORTANT) Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H';CWE-362;*CWE-416;CWE-415;*CWE-401;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7';DESCR 'This is a race term with a concrete skb use after free and possible double release. The cleanup path can free wx ptp_tx_skb after the PTP worker has obtained its pointer, after which the worker may pass freed memory to skb_tstamp_tx and release the same reference again. For the CVSS the PR:L value is selected because reliable triggering requires a local process or kernel consumer able to request hardware Tx timestamps on a supported Wangxun interface. AC:H reflects the need to win a timing window between transmission, worker processing, timeout cleanup, quiesce, or DMA error handling. The issue is not proven to be directly network reachable. Availability impact includes kernel crash, while confidentiality and integrity impact are plausible because the demonstrated UAF and double release can corrupt kernel memory ownership. Automated impact decision path. The original SimpleNet classifier selected MODERATE_KPANIC. The primary LLM estimated paranoid CVSS 7 and the production ActionableScore returned 5 with recommendation Actionable Moderate / Strong Important candidate requiring manual review. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were CVSS and initial triage stage MODERATE_KPANIC to MODERATE_KPANIC because the CVSS score, vector or bug class threshold rule was applied. final reconciliation stage MODERATE_KPANIC to IMPORTANT because a specific evidence based protection or manual review veto was applied and KP specialist did not establish a qualifying panic. The legacy KP specialist produced a review artifact and its decision was processed by the applicable KP rules. The legacy FD or DH downgrade specialist has no review artifact for this run. Exact triggered rule markers were INCREASED_TO_HIGH_BASED_ON_GUESSCVSS and LOWERED_FROM_HIGH_BASED_ON_NULLPTR and TEMP_KPANIC_MERGE_IMPORTANT_VETO and KPANIC_UNSUPPORTED_REMOVED. The independent weaker Aegis shadow evaluated CVSS 2.5 and ActionableScore 6 with primitive class CLASS_B and manual review REQUIRED. Its independently reconciled impact was IMPORTANT. Cross model aggregation changed the production result under an enabled evidence gated merge rule. The final reported impact is IMPORTANT.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate / Strong Important candidate requiring manual review (with actual score 5) MAYBE REMOTE OOB LOCK INIT RACE LEAK ERRORPATH UAF NETWORK SKB DMAorINTERRUPT HARDWARE LINUS TEST INCREASED_TO_HIGH_BASED_ON_GUESSCVSS LOWERED_FROM_HIGH_BASED_ON_NULLPTR TEMP_KPANIC_MERGE_IMPORTANT_VETO KPANIC_UNSUPPORTED_REMOVED - - checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=5
ActionableScoreLower=4
PrimitiveClass=CLASS_B
RealUAF=YES
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=YES
ManualReview=REQUIRED
AutoDowngradeAllowed=NO
RequiresHostUID0=UNKNOWN
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO
1. ActionableScore
* Raw base score: 4.
* Conservative score: 4. The general UAF floor of 4 does not change it. The floor of 5 for repeated release is not forced because the supplied evidence identifies a high-complexity race and does not establish complete below-host-admin reachability.
* Raw paranoid score: 5.
* Paranoid score: 5; no cap or floor changes it.
* Final recommended bucket: **Actionable Moderate / Strong Important candidate requiring manual review**::
2. Signal breakdown
* +2 real UAF: cleanup can release `wx->ptp_tx_skb` after the worker copied its pointer, after which the worker uses that stale pointer.
* +1 concrete repeated release: cleanup's `dev_kfree_skb_any()` can end the timestamp reference's lifetime; the same pointer survives in the worker and reaches another `dev_kfree_skb_any()`.
* +1 structured stale-object leverage: before the second release, the worker passes the stale, attacker-originated packet skb to `skb_tstamp_tx()`, which consumes active skb state. This is distinct from the refcount mutation.
* +1 plausible kernel crash/strong DoS from stale skb processing or double release. No separate availability point is awarded.
* -1 hard timing requirement: supplied triage evidence specifically characterizes reliable triggering as requiring a race between worker and cleanup/error/quiesce paths.
* Paranoid +1: the second `dev_kfree_skb_any()` performs a write-like lifetime/refcount mutation through storage whose skb lifetime may already have ended.
Controlled reclaim, arbitrary write, disclosure, C/I impact, callback control, and LPE are not shown. The repeated-release and structured-consumption points cover distinct operations and are not double-counted.
3. Reachability analysis
A local sender or kernel consumer can originate an skb requesting hardware Tx timestamps on supported Wangxun hardware. However, the evidence does not establish who can complete all prerequisite timestamp configuration, including `HWTSTAMP_TX_ON`, or which capability namespace governs it. Below-host-admin and fully namespace-scoped reachability therefore remain unknown. No direct remote trigger is shown. Supported physical hardware is required, but it is not proven rare. The race is repeatable in principle but supplied evidence rates reliable timing as difficult.
4. Primitive and severity reading
This is an active structured-object UAF, not fixed stale storage. It is broader than a shallow cleanup fault: the worker calls `skb_tstamp_tx()` on the freed skb and then performs a second lifetime release. The first release may destroy the skb, the exact pointer survives, and the second operation mutates its lifetime state.
This is CLASS_B rather than CLASS_A because controlled reuse, directed corruption, or refcount takeover is not demonstrated. Crash and reference leakage are supported; stronger exploitation remains unresolved. The concrete stale structured consumption plus repeated release warrants Important review and prevents automatic downgrade.
5. One-sentence report phrase
A cleanup/worker race can feed a freed Tx-timestamp skb into `skb_tstamp_tx()` and then release the same reference again, creating an active-skb UAF and double-release primitive.
6. Manual review advice
MANUAL CHECK REQUIRED
The exact post-lifetime structured use and second refcount mutation leave material exploit leverage unresolved despite uncertain privilege and difficult timing.
7. Call-site confidence
Call-site confidence: high
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: net: libwx: fix races in Tx timestamp handling [ Upstream
Commit: e78b95cfd5df25d0c562aaef95d3c7fe6c7e0e66
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e78b95cfd5df25d0c562aaef95d3c7fe6c7e0e66
Changed files:
drivers/net/ethernet/wangxun/libwx/wx_hw.c
drivers/net/ethernet/wangxun/libwx/wx_lib.c
drivers/net/ethernet/wangxun/libwx/wx_ptp.c
drivers/net/ethernet/wangxun/libwx/wx_type.h
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=e78b95cfd5df25d0c562aaef95d3c7fe6c7e0e66
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-98562 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98562
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:L/UI:N/S:U/C:L/I:L/A:H
The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
The Best / paranoid CVSS score: 7
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: 4
Paranoid ActionableScore: 5
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: IMPORTANT
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): IMPORTANT
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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