[CVE-2026-98614][MODERATE REGULAR] sctp: avoid livelock while updating retransmit path [ Upstream

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

CVE: CVE-2026-98614
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: sctp: avoid livelock while updating retransmit path [ Upstream
Commit: 3fe624c3843694ab096fdb198526ba0c659febbe
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3fe624c3843694ab096fdb198526ba0c659febbe
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98614
Analysis date: Sat, 24 Oct 2026 06:59:37 -0400
ActionableScore: 3
ActionableScore lower bound: unknown
Actionable bucket: Borderline / manual review recommended
Manual review required: YES

Summary:
A remotely influenced SCTP transport-state configuration can trap retransmission-path selection in an infinite loop, causing a kernel CPU stall without shown memory corruption.

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

The original Linux kernel CVE announcement for CVE-2026-98614 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98614

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 REGULAR
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
======================================================================

CVE-2026-98614	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-98614 CHECK WITH IMPACT FROM ORIG NN MODERATE | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=1 LEGACY=MODERATE RESULT=DIFF (final Legacy and Aegis differ; FINAL: MODERATE, Aegis: MODERATE_KPANIC)	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H';*CWE-835;**CWE-400;Other CVSS 'AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '7.5';DESCR 'An SCTP logic error in sctp_assoc_update_retran_path can cause a livelock because SCTP_UNCONFIRMED transports are skipped before the iterator tests whether it returned to retran_path. If every remaining transport is UNCONFIRMED, kernel execution can remain in the walk and cause a CPU stall or watchdog soft lockup, resulting in denial of service without an identified memory corruption primitive. For the CVSS the PR:N value reflects that a network peer may interact with an existing SCTP association without credentials on the victim host, although reaching the required state depends on SCTP multihoming and path state transitions. Confidentiality and integrity are not affected based on the available code evidence, while availability can be high if the loop stalls kernel execution. Automated impact decision path. The original SimpleNet classifier selected MODERATE_KPANIC. The primary LLM estimated paranoid CVSS 7.5 and the production ActionableScore returned 3 with recommendation Borderline / manual review recommended. 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. ActionableScore thresholds stage MODERATE_KPANIC to MODERATE because the ActionableScore threshold rule was applied. The legacy KP specialist has no review artifact for this run. The legacy FD or DH downgrade specialist has no review artifact for this run. Exact triggered rule markers were INCREASED_TO_MODERATE7_BASED_ON_GUESSCVSS and DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 and V41_INHERITED_KPANIC_PROMOTION_BLOCKED and MANUAL_REVIEW_REQUIRED. The independent weaker Aegis shadow evaluated CVSS 3.7 and ActionableScore 1 with primitive class CLASS_C and manual review REQUIRED. Its independently reconciled impact was MODERATE_KPANIC. The models disagreed but the aggregation rules retained the production result. The final reported impact is MODERATE.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline / manual review recommended (with actual score 3)	MAYBE	SIMPLEFIX NETWORK LINUS TEST  INCREASED_TO_MODERATE7_BASED_ON_GUESSCVSS DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 V41_INHERITED_KPANIC_PROMOTION_BLOCKED MANUAL_REVIEW_REQUIRED	-	-	checked

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

ActionableScore=3
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES
RequiresHostUID0=UNKNOWN
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO

1. ActionableScore

* Raw base score: 3.
* Conservative score: 3; no floor or cap applied.
* Raw paranoid score: 3.
* Paranoid score: 3; no additional technically supported primitive.
* Final recommended bucket: **Borderline / manual review recommended**::

2. Signal breakdown

* +2 Remote/net-reachable: an SCTP peer can plausibly influence an existing association’s transport states and retransmission-path update, although the complete all-UNCONFIRMED transition is not demonstrated by the patch.
* +1 Reliable kernel DoS: the loop can fail to reach its wraparound check and run indefinitely, plausibly causing CPU stall or watchdog soft lockup.
* No timing penalty: this is a deterministic state-dependent loop, not evidence of a narrow race.
* No extra availability point: the stall/soft-lockup is the same DoS already counted.
* No corruption points: the patch shows neither OOB access, UAF, stale-object mutation, nor attacker-controlled write.
* NEW52/B5-R does not apply: there is no heap OOB write or retry-accumulated offset.
* Authorization signals are not applicable; no DENY-to-ALLOW decision exists.

3. Reachability analysis

A network peer may participate in SCTP association and path-state changes without local credentials. However, supplied code does not fully establish that the peer alone can force every remaining transport, including `retran_path`, into `SCTP_UNCONFIRMED` and invoke this update. Therefore effective host privilege and namespace scope remain unknown rather than proven host-admin-free. No special hardware or race is required; SCTP multihoming and the requisite path-state sequence are prerequisites.

4. Primitive and severity reading

The exact defect is a loop-termination ordering error: `continue` bypasses the full-pass check for every unconfirmed transport. The secondary NULL guard prevents replacing an existing retransmit path with NULL, but no reachable NULL dereference is independently shown.

This is CLASS_C availability behavior. The shown effect is livelock/CPU stall; memory corruption, confidentiality/integrity impact, authorization bypass, and useful post-crash leverage are unsupported. ImportantCandidate is NO and auto-downgrade is allowed because no unresolved corruption or security-boundary primitive remains.

5. One-sentence report phrase

A remotely influenced SCTP transport-state configuration can trap retransmission-path selection in an infinite loop, causing a kernel CPU stall without shown memory corruption.

6. Manual review advice

MANUAL CHECK RECOMMENDED

Confirm whether an unauthenticated SCTP peer can reliably create the complete all-UNCONFIRMED state and trigger the update path.

7. Call-site confidence

Call-site confidence: medium

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

Patch: sctp: avoid livelock while updating retransmit path [ Upstream
Commit: 3fe624c3843694ab096fdb198526ba0c659febbe
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3fe624c3843694ab096fdb198526ba0c659febbe

Changed files:
  net/sctp/associola.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=3fe624c3843694ab096fdb198526ba0c659febbe

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

The original Linux kernel CVE announcement for CVE-2026-98614 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98614

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:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS vector: AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 7.5

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: 3

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: NO
Published priority for this report (same as in Subject): MODERATE REGULAR

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).