* [CVE-2026-98338][LOW] wifi: cfg80211: ibss: ref BSS entry for joined event [ Upstream
@ 2026-10-10 11:27 21% AL-KERNEL
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From: AL-KERNEL @ 2026-10-10 11:27 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-98338
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: wifi: cfg80211: ibss: ref BSS entry for joined event [ Upstream
Commit: b0e3f019e461ac42e45aa3ec1216cefaca2f4a8b
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=b0e3f019e461ac42e45aa3ec1216cefaca2f4a8b
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98338
Analysis date: Sat, 10 Oct 2026 07:27:20 -0400
ActionableScore: 1
ActionableScore lower bound: unknown
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-2026-98338 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98338
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-2026-98338 LOW https://www.kernelcve.org/list/?q=CVE-2026-98338 CHECK WITH IMPACT FROM ORIG NN MODERATE | AEGIS IMPACT LOW AEGIS_AS=0 LEGACY=LOW RESULT=SAME (legacy and Aegis reconciliation agree; DECISION: both LOW) Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';CWE-362;CWE-367;*CWE-664;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'A race in cfg80211 IBSS event handling can occur because the joined event records only the BSSID and channel while the associated BSS entry is looked up later by cfg80211_event_work. A concurrent scan using NL80211_SCAN_FLAG_FLUSH can remove the BSS entry before deferred event processing, causing WARN_ON and preventing normal completion of the IBSS joined event. No stale cfg80211_bss pointer is dereferenced in the affected path, so the available code does not establish a use-after-free, out-of-bounds access, or other memory corruption primitive. For the CVSS the PR:L in the paranoid score reflects environments where WiFi management is delegated to a local service, container root, or restricted user rather than requiring unrestricted host administrator access. The race requires a timing window between IBSS join notification and a flushing scan, so AC:H is appropriate. The issue is not directly network reachable because the demonstrated trigger requires local wireless control operations rather than only receiving WiFi traffic. The realistic impact is a warning and disruption of IBSS state or connectivity. A kernel crash is possible only on systems configured to panic on warnings, which supports A:H solely as a paranoid environmental upper bound.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1) MAYBE REMOTE LOCK DANGER SYZBOT DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 KPANIC_UNSUPPORTED_REMOVED - - checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=1
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES
RequiresHostUID0=UNKNOWN
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO
1. ActionableScore
* Raw conservative score: 1
* Conservative score: 1
* Raw paranoid score: 1
* Paranoid score: 1
* No floor or cap was applied.
* Final recommended bucket: **Ordinary Moderate**::
2. Signal breakdown
* +1 Availability impact: losing the BSS entry before deferred event processing causes `WARN_ON`, aborts normal IBSS joined-event handling, and may disrupt IBSS state or connectivity.
* +0 Race: the scan-flush and event-work interleaving is established, but a materially narrow or uncontrollable race is not established, so no timing penalty applies.
* +0 WARN: `WARN_ON` is not independently scored as a kernel crash. Fatal behavior would depend on an environmental setting such as `panic_on_warn`.
* +0 Lifetime corruption: the old event stores BSSID and channel values, not a borrowed `cfg80211_bss` pointer. The later lookup returns NULL after removal, so no stale BSS object is dereferenced.
* +0 Exploitation leverage: no controlled reclaim, OOB access, arbitrary write, repeated release, refcount mutation, disclosure, or privilege escalation is demonstrated.
* +0 Remote reachability: receiving wireless traffic alone is not shown to execute the complete race. A local scan-flush control operation is also involved.
* B5-R does not apply because there is no heap OOB write, retry-accumulated offset, or later consumption of corrupted descriptors.
* B3-PENDING does not apply because no shared-backing or file-backed write occurs.
* B4-PENDING does not apply because no authorization guard changes from DENY to ALLOW.
3. Reachability analysis
The IBSS joined notification originates from the wireless driver, while the competing removal can result from a scan using `NL80211_SCAN_FLAG_FLUSH`. The supplied evidence does not establish which credentials are sufficient to perform the complete join and flushing-scan sequence, so host-admin and namespace-scoped reachability remain unknown.
No direct remote trigger is established. The attacker would need influence over local wireless control operations and the ordering relative to deferred cfg80211 event processing. The race is reproducible enough for syzbot to report it, but the evidence does not establish either ordinary unprivileged reachability or an unusually hard one-shot race. No mandatory rare physical hardware prerequisite is established by the patch.
4. Primitive and severity interpretation
The exact defect is a race-induced lookup failure. A BSS entry valid when the event is queued can be removed before `cfg80211_event_work` performs `cfg80211_get_bss()`. The lookup then returns NULL, triggers a warning, and terminates joined-event processing.
This is not a real UAF. The vulnerable event does not retain a stale `cfg80211_bss` pointer, and the removed BSS is not subsequently dereferenced through the event. The fix obtains a referenced BSS earlier and transfers that reference to `current_bss`, but this closes a lookup-lifetime gap rather than repairing demonstrated post-free access.
The issue is therefore CLASS_C invalid-state and availability behavior. Its demonstrated consequence is warning and possible IBSS connectivity disruption. Kernel panic is only an environmental possibility on systems configured to panic on warnings. There is no meaningful unresolved corruption or authorization primitive, so ImportantCandidate is NO and automatic downgrade is allowed.
5. One-sentence report phrase
A race between deferred cfg80211 IBSS joined-event processing and a flushing scan can remove the required BSS entry, causing a warning and possible IBSS connectivity disruption without demonstrating use-after-free or other kernel memory corruption.
6. Manual review recommendation
NO MANUAL CHECK NEEDED
The visible call path establishes a NULL lookup and aborted event handling, but no stale-object dereference, write primitive, authorization bypass, or unresolved lifetime mutation.
7. Call-site confidence
Call-site confidence: high
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: wifi: cfg80211: ibss: ref BSS entry for joined event [ Upstream
Commit: b0e3f019e461ac42e45aa3ec1216cefaca2f4a8b
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=b0e3f019e461ac42e45aa3ec1216cefaca2f4a8b
Changed files:
net/wireless/ibss.c
net/wireless/util.c
net/wireless/core.c
net/wireless/core.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=b0e3f019e461ac42e45aa3ec1216cefaca2f4a8b
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-98338 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98338
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:N/A:L
The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
The Best / paranoid CVSS score: 4.7
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: unknown
Paranoid ActionableScore: 1
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 [email protected] (and both
send reply to CVE record itself too and see "reply" button below for howto reply).
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