[CVE-2026-98947][LOW] vsock: Fix memory leak in vmci_transport_recv_dgram_cb() [ Upstream

[CVE-2026-98947][LOW] vsock: Fix memory leak in vmci_transport_recv_dgram_cb() [ Upstream

[AL-KERNEL]

CVE: CVE-2026-98947
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: vsock: Fix memory leak in vmci_transport_recv_dgram_cb() [ Upstream
Commit: 0f8e2b2045355a0ee2008125e573435504b13cee
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=0f8e2b2045355a0ee2008125e573435504b13cee
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98947
Analysis date: Mon, 26 Oct 2026 16:53:36 -0400
ActionableScore: 2
ActionableScore lower bound: 1
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
A low-privilege local VMCI/VSOCK closure race can strand received skbs and cumulatively leak kernel memory.

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

The original Linux kernel CVE announcement for CVE-2026-98947 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98947

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-2026-98947	LOW	https://www.kernelcve.org/list/?q=CVE-2026-98947 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT LOW AEGIS_AS=1 LEGACY=LOW RESULT=SAME (final reconciliation agrees; 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-401;CWE-362;*CWE-664;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'A race during VMCI datagram socket closure can leave an skb in sk_receive_queue after the normal receive queue cleanup. The demonstrated primitive is persistent kernel memory retention rather than UAF or another memory corruption primitive. For the CVSS the PR:L value is used because reliable triggering requires a local process able to create and close a VSOCK datagram socket while arranging concurrent VMCI datagram delivery. Availability impact is low in the base case because each successful race leaks a limited object and host wide exhaustion requires repeatable accumulation over many operations. The paranoid score allows high availability impact if the race can be reproduced reliably enough to exhaust kernel memory, but confidentiality and integrity remain unaffected. Automated impact decision path. The original SimpleNet classifier selected LOW. The primary LLM estimated paranoid CVSS 4.7 and the production ActionableScore returned 2 with recommendation Ordinary Moderate. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. No severity changing production threshold or specialist override was recorded. 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. The independent weaker Aegis shadow evaluated CVSS 2.5 and ActionableScore 1 with primitive class CLASS_C and manual review REQUIRED. Its independently reconciled impact was LOW. The shadow agreed with the final production impact and aggregation did not change that impact. The final reported impact is LOW.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 2)	MAYBE	LEAK SKB HARDWARE PACKET 	-	-	checked

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

ActionableScore=2
ActionableScoreLower=1
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES
RequiresHostUID0=NO
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO

1. ActionableScore

* Raw base score: 1.
* Conservative score: 1; no floor or cap applied.
* 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: an skb arriving during socket closure can move from backlog into `sk_receive_queue` after the earlier purge and remain there until the added destructor purge.
* +1 — Local low-privilege trigger: supplied evidence supports a local process creating/closing a VSOCK datagram socket while arranging concurrent delivery.
* -1 — Hard timing requirement: successful leakage requires datagram delivery in the socket-closure window.
* Paranoid +1 — Repeated successful races can accumulate unreclaimed skbs and plausibly create memory pressure. Host-wide exhaustion is not demonstrated, so this is not included in the conservative score.
* No UAF, OOB write, shared-backing write, authorization bypass, disclosure, integrity violation, or separate crash primitive is shown. B5-R, B3-PENDING, and B4-PENDING do not apply.

3. Reachability analysis

The supported actor is a below-host-admin local process using a VMCI-backed VSOCK datagram socket; host UID 0 or a namespace capability is not required by the supplied evidence. VMCI transport availability and concurrent datagram delivery are prerequisites. The attacker can repeat socket creation and closure, but each leak still depends on winning the closure/delivery race. No separate privileged setup beyond an available VMCI/VSOCK environment is established.

4. Primitive and severity reading

The exact primitive is persistent retention of an skb left in the receive queue, fixed by purging that queue in `vsock_sk_destruct()`. This is a resource-lifetime cleanup defect, not stale-object use or memory corruption. The proven effect is a bounded leak per successful race; cumulative kernel-memory exhaustion is plausible but unproven. It is therefore CLASS_C, not an Important candidate, and ordinary Moderate auto-downgrade is allowed.

5. One-sentence report phrase

A low-privilege local VMCI/VSOCK closure race can strand received skbs and cumulatively leak kernel memory.

6. Manual review advice

NO MANUAL CHECK NEEDED

The patch establishes only an availability-oriented resource leak with no unresolved corruption or security-boundary primitive.

7. Call-site confidence

Call-site confidence: high

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

Patch: vsock: Fix memory leak in vmci_transport_recv_dgram_cb() [ Upstream
Commit: 0f8e2b2045355a0ee2008125e573435504b13cee
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=0f8e2b2045355a0ee2008125e573435504b13cee

Changed files:
  net/core/skbuff.c
  kernel/irq/manage.c
  kernel/kthread.c
  arch/x86/entry/entry_64.S
  net/vmw_vsock/af_vsock.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=0f8e2b2045355a0ee2008125e573435504b13cee

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

The original Linux kernel CVE announcement for CVE-2026-98947 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98947

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: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: 1
  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 alexanjelausa@gmail.com (and both
send reply to CVE record itself too and see "reply" button below for howto reply).