* [CVE-2026-98285][LOW] net: bridge: vlan: fix bugs caused by switchdev deletion errors [ Upstream
@ 2026-10-10 22:44 21% AL-KERNEL
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From: AL-KERNEL @ 2026-10-10 22:44 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-98285
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: net: bridge: vlan: fix bugs caused by switchdev deletion errors [ Upstream
Commit: ed3ea86db736a30bebf49b947c42730e8451bcd2
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ed3ea86db736a30bebf49b947c42730e8451bcd2
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98285
Analysis date: Sat, 10 Oct 2026 18:44:49 -0400
ActionableScore: 2
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-2026-98285 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98285
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-2026-98285 LOW https://www.kernelcve.org/list/?q=CVE-2026-98285 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT LOW AEGIS_AS=1 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-703;*CWE-772;**CWE-476;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '4.7';DESCR 'A switchdev error during bridge VLAN deletion could abort the software cleanup path and leave the bridge VLAN state inconsistent. Subsequent VLAN flush operations could retain resources or reach a NULL pointer dereference in error handling, resulting in a kernel crash and local denial of service. For the CVSS the PR:L value is used for the paranoid score because VLAN administration may be delegated to a restricted service, container root, or another user context with CAP_NET_ADMIN. The normal host configuration is better represented by PR:H because bridge and switchdev VLAN management usually requires administrative control. AC:H is used because reliable triggering depends on reaching a switchdev deletion error on a compatible device or driver while performing VLAN deletion or flush operations. The issue is not directly network reachable because ordinary packet traffic does not invoke the vulnerable control plane deletion path. The demonstrated impact is availability loss. No controlled read, controlled write, UAF, or other memory corruption primitive is established, so confidentiality and integrity remain unaffected.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 2) MAYBE NULLPTR SIMPLEFIX LEAK - - checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=2
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: 2
* Conservative score: 2
* Raw paranoid score: 2
* Paranoid score: 2
* No floor or cap applied.
* Final recommended bucket: **Ordinary Moderate**::
2. Signal breakdown
* +1 Concrete persistent kernel resource leak. A switchdev deletion error makes `__vlan_del()` return before software VLAN cleanup, and the commit explicitly identifies memory leaks during flush.
* +1 Reliable kernel crash or strong DoS. The flush error-reporting path dereferences `p` even when processing a bridge VLAN without a port, producing a NULL-pointer dereference.
* +0 Inconsistent VLAN state. This is part of the same failed-cleanup defect and does not independently establish corruption, disclosure, or a security-boundary bypass.
* No UAF, OOB write, controlled write, controlled reclaim, repeated release, or refcount mutation is established.
* No extra availability point is awarded because the NULL dereference is already counted as the crash consequence, and host-wide resource exhaustion from the leak is not established.
* No confidentiality or integrity signal is awarded. The patch establishes incomplete deletion and an invalid dereference, not access to protected data or unauthorized modification.
* No remote-reachability signal is awarded. Packet traffic does not directly invoke bridge VLAN deletion.
* B5-R does not apply because there is no heap OOB write or retry-accumulated offset.
* B3-PENDING does not apply because no shared-backing write is present.
* B4-PENDING does not apply because no authorization decision changes from DENY to ALLOW.
3. Reachability analysis
The trigger requires a bridge VLAN deletion or flush to reach a switchdev callback that returns an error. Bridge VLAN administration normally passes through rtnetlink and a `CAP_NET_ADMIN` check associated with the relevant network namespace.
The supplied evidence does not establish whether the complete vulnerable sequence can be performed inside an attacker-created namespace. In particular, the switchdev device, bridge, and offload callback may involve host-owned device state. Therefore `HostAdminRequired` and `NamespaceScopedPrivilege` remain `UNKNOWN`, with no privilege penalty or unprivileged-trigger bonus.
A compatible switchdev path and an existing bridge VLAN configuration are prerequisites. The evidence does not prove that such hardware is rare or physical-only, so no hardware or niche-subsystem penalty is applied. This is an ordered error path, not a race, and no timing penalty applies.
4. Primitive and severity interpretation
The exact primitive is incomplete software VLAN deletion followed by either retained resources or a NULL-pointer dereference in flush error reporting. The dereference is an invalid crash-oriented access, not use-after-free or an attacker-directed write.
There is no concrete repeated release or refcount operation. No first lifetime-ending release followed by a second mutation of the same reference exists. The affected VLAN state is active kernel state, but the demonstrated consequence remains failed cleanup, leakage, and immediate invalid dereference rather than useful post-lifetime structured-object consumption.
This is `CLASS_C`. The demonstrated impact is local denial of service and resource retention. Stronger consequences such as arbitrary kernel corruption, privilege escalation, or authorization bypass are unsupported.
`ImportantCandidate=NO` because no Important-preserving corruption or boundary primitive is present. `AutoDowngradeAllowed=YES` because the issue is a constrained control-plane cleanup failure with crash and leak consequences, and no meaningful unresolved exploitation leverage remains.
5. One-sentence report phrase
A switchdev error can abort bridge VLAN software cleanup, leaking VLAN resources and causing a NULL-pointer dereference during flush error handling, but no UAF, controlled corruption, remote trigger, or authorization bypass is established.
6. Manual review recommendation
NO MANUAL CHECK NEEDED
The patch supports automated classification as a control-plane cleanup and error-handling DoS without an Important-preserving primitive.
7. Call-site confidence
Call-site confidence: high
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: net: bridge: vlan: fix bugs caused by switchdev deletion errors [ Upstream
Commit: ed3ea86db736a30bebf49b947c42730e8451bcd2
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ed3ea86db736a30bebf49b947c42730e8451bcd2
Changed files:
net/bridge/br_vlan.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=ed3ea86db736a30bebf49b947c42730e8451bcd2
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-98285 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98285
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:H
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: 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 [email protected] (and both
send reply to CVE record itself too and see "reply" button below for howto reply).
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