[CVE-2026-99206][IMPORTANT] scsi: target: iscsi: Fix race in discovery auth updates [ Upstream

[AL-KERNEL <alkernel@kernelcve.org>]

CVE: CVE-2026-99206
Priority: IMPORTANT
AL-KERNEL base severity: IMPORTANT
KPANIC flag: NO
Patch: scsi: target: iscsi: Fix race in discovery auth updates [ Upstream
Commit: 9b07828b133b326cb4fb59f144ca37f8db535999
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=9b07828b133b326cb4fb59f144ca37f8db535999
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99206
Analysis date: Fri, 30 Oct 2026 10:52:06 -0400
ActionableScore: 5
ActionableScore lower bound: unknown
Actionable bucket: Actionable Moderate / Strong Important candidate requiring manual review
Manual review required: YES

Summary:
Concurrent discovery-auth configfs updates can double-free the same heap-backed parameter value, causing crash-capable allocator corruption with unresolved exploit leverage.

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ABOUT THIS REPORT
======================================================================

The original Linux kernel CVE announcement for CVE-2026-99206 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99206

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.

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AL-KERNEL CLASSIFICATION RESULT
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CVE-2026-99206	IMPORTANT	https://www.kernelcve.org/list/?q=CVE-2026-99206 CHECK WITH IMPACT FROM ORIG NN IMPORTANT | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=3 LEGACY=IMPORTANT RESULT=DIFF INDEPENDENT_LEGACY=IMPORTANT INDEPENDENT_RESULT=DIFF TEMP_KPANIC_MERGE=IMPORTANT_WINS_DISAGREEMENT PRE_MERGE_LEGACY=IMPORTANT (final Legacy and Aegis differ; FINAL: IMPORTANT, Aegis: MODERATE_KPANIC)	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-415;CWE-667;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7';DESCR 'A race between concurrent configfs writes to discovery AuthMethod allows both callers to observe and free the same parameter value in iscsi_update_param_value, creating a kernel double free and potential heap corruption. The reliably demonstrated impact is a local kernel crash, while allocator corruption provides a plausible but unproven path to privilege escalation or data impact. AC:H reflects the need to win a concurrency window between two parameter updates. For the CVSS the PR:H base value reflects that target configfs writes normally require administrative access. For the CVSS the PR:L paranoid value covers delegated target management, a service account, or a reduced capability container context with write access to the affected configfs item. The issue is local and is not directly reachable through iSCSI network traffic. Automated impact decision path. The original SimpleNet classifier selected IMPORTANT. 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 final reconciliation stage IMPORTANT to IMPORTANT because KP specialist did not establish a qualifying panic. The legacy KP specialist has no review artifact for this run. The legacy FD or DH downgrade specialist produced a review artifact and its decision was processed by the applicable downgrade and preservation rules. Exact triggered rule markers were TEMP_KPANIC_MERGE_IMPORTANT_WINS and KPANIC_UNSUPPORTED_REMOVED. The independent weaker Aegis shadow evaluated CVSS 3.0 and ActionableScore 3 with primitive class CLASS_B and manual review REQUIRED. Its independently reconciled impact was MODERATE_KPANIC. 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	RACE LEAK UAF LINUS TEMP_KPANIC_MERGE_IMPORTANT_WINS KPANIC_UNSUPPORTED_REMOVED	-	-	checked

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

ActionableScore=5
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: 3.
* Conservative score: 5. REAL UAF FLOOR 5 applies because the first free can end the value’s lifetime and a concurrent caller frees the exact same stale allocation.
* Raw paranoid score: 4.
* Paranoid score: 5. The same floor applies; no separate score divergence remains.
* Final recommended bucket: **Actionable Moderate / Strong Important candidate requiring manual review**::

2. Signal breakdown

* +2 real lifetime violation: concurrent `iscsi_update_param_value()` calls can free the same parameter value, establishing a double-free.
* +1 concrete repeated release: the first free ends the old value’s lifetime; another caller retaining that same value performs the second free.
* +1 plausible kernel crash/strong DoS from double-free allocator corruption.
* -1 hard concurrency window: two configfs updates must overlap during lookup and replacement.
* Paranoid +1: the second free actively mutates allocator/lifetime metadata through already-freed storage; this is not merely theoretical reclaim.
* No controlled reclaim, attacker-selected target/payload, arbitrary write, disclosure, or LPE is shown. No additional availability or C/I points are awarded.
* The repeated-free fact is not also counted as Weak LPE or structured stale-object leverage.

3. Reachability analysis

The trigger is local concurrent writing of the discovery authentication configfs attribute, not remote iSCSI traffic. The evidence says such target configuration normally requires administrative access, but does not prove that every deployment requires effective host-admin powers; delegated target-management access remains possible. Therefore both host-admin and namespace scope are unresolved. The attacker can influence concurrency by issuing separate configfs writes, although winning the replacement race may require repeated attempts. Existing iSCSI target/configfs setup is required.

4. Primitive and severity reading

This is a confirmed heap double-free: two callers retain the same old parameter-value pointer, one frees it, and the other performs a second lifetime-ending operation. It is stronger than an ordinary stale cleanup dereference but remains CLASS_B because controlled reclaim, directed corruption, and a useful adjacent victim are not shown. Crash and allocator corruption are supported; privilege escalation is speculative. The concrete post-lifetime free leaves material exploit leverage unresolved, so ImportantCandidate is YES and automatic downgrade is unsafe. This is not an authorization-decision bypass despite affecting an authentication configuration value.

5. One-sentence report phrase

Concurrent discovery-auth configfs updates can double-free the same heap-backed parameter value, causing crash-capable allocator corruption with unresolved exploit leverage.

6. Manual review advice

MANUAL CHECK REQUIRED

Review allocator behavior, repeatability, delegated configfs access, and whether the freed value can be predictably reclaimed before the second free.

7. Call-site confidence

Call-site confidence: high

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

Patch: scsi: target: iscsi: Fix race in discovery auth updates [ Upstream
Commit: 9b07828b133b326cb4fb59f144ca37f8db535999
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=9b07828b133b326cb4fb59f144ca37f8db535999

Changed files:
  drivers/target/iscsi/iscsi_target_configfs.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=9b07828b133b326cb4fb59f144ca37f8db535999

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

The original Linux kernel CVE announcement for CVE-2026-99206 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99206

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