[CVE-2026-64011][MODERATE 7.0] nfc: llcp: Fix use-after-free in llcp_sock_release() [ Upstream

[CVE-2026-64011][MODERATE 7.0] nfc: llcp: Fix use-after-free in llcp_sock_release() [ Upstream

[AL-KERNEL]

CVE: CVE-2026-64011
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: nfc: llcp: Fix use-after-free in llcp_sock_release() [ Upstream
Commit: 89ba026747019ee643d29407435ddc118e6ca908
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=89ba026747019ee643d29407435ddc118e6ca908
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64011
Analysis date: Sun, 19 Jul 2026 13:42:01 -0400
ActionableScore: 5
ActionableScore lower bound: 4
Actionable bucket: Actionable Moderate at minimum
Manual review required: YES

Summary:
A use-after-free in the NFC LLCP socket release path can leave a connecting socket on the wrong list after release, allowing later kernel list processing to access freed memory and potentially cause a local kernel crash, with privilege escalation requiring manual review but not demonstrated.

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

The original Linux kernel CVE announcement for CVE-2026-64011 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64011

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 7.0
Manual review required: YES

A detailed explanation of the methodology and priority rules is included
at the end of this message.

======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================

CVE-2026-64011	MODERATE	CHECK WITH IMPACT FROM ORIG NN 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:H/I:H/A:H';*CWE-416;*CWE-672;CWE-763;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7';DESCR 'A use-after-free can occur in the NFC/LLCP socket release path because llcp_sock_release() removed a socket from the normal local sockets list even when the socket was still in LLCP_CONNECTING state and actually linked on the connecting_sockets list. This can leave a stale socket reference in the connecting list after the object is released, allowing later LLCP list processing to touch freed kernel memory. For the CVSS the PR:L is used because reliable triggering requires a local process that can create and close NFC LLCP sockets, while no full administrator privileges are necessarily implied. The issue is not directly network reachable as AV:N because a remote NFC peer cannot by itself execute the local socket release path, although NFC hardware and an LLCP environment may be needed to reach the connecting state. Impact is at least local denial of service via kernel crash. In the paranoid score, C:H/I:H/A:H is used because the confirmed bug class is use-after-free and stale kernel list references can be a plausible memory corruption candidate requiring manual review.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 5)  SKIP CVE-2026-64011 UNKNOWN SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	LOCK DANGER UAF LINUS KPANIC 	-	-	checked

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

ActionableScore=5
ActionableScoreLower=4

## 1. ActionableScore

* Conservative score: 4
* Paranoid score: 5
* Final recommended bucket: **Actionable Moderate at minimum**

## 2. Signal breakdown

Conservative signals:

* Local unprivileged trigger: +1. A local process can plausibly create and close NFC LLCP sockets, assuming NFC/LLCP is available.
* Generic memory corruption: +2. The commit explicitly fixes a use-after-free caused by leaving a socket linked on the wrong list.
* Real lifetime corruption: +1. This is a stale lifetime/list membership bug where a released socket can remain reachable via `connecting_sockets`.
* Reliable kernel crash / strong DoS: +1. Later traversal or cleanup of the stale socket reference can plausibly crash the kernel.
* Rare and difficult-to-reach subsystem/configuration: -1. NFC LLCP is not a broadly deployed default server-side subsystem and usually requires NFC hardware/support.

Paranoid additional signal:

* Weak LPE concern: +1. The stale list reference points to freed kernel socket memory, and local socket churn may make reuse/reclaim scenarios worth manual review, although no controlled reclaim or write primitive is demonstrated in the patch.

Not counted:

* Remote reachable: +0. A remote NFC peer does not directly invoke local `llcp_sock_release()`.
* Strong LPE plausibility: +0. No attacker-controlled reclaim, callback dispatch, arbitrary write, or type confusion is shown.
* Confidentiality/Integrity as demonstrated impact: +0 conservative. The evidence supports UAF and DoS first, with C/I only as paranoid triage concern.

## 3. Reachability analysis

The likely trigger is local: create an NFC LLCP socket, reach `LLCP_CONNECTING`, then close/release it before it is moved to the normal socket list. This does not require network reachability in the CVSS AV:N sense. It may require NFC hardware, NFC stack availability, and an LLCP-capable environment, which lowers broad exposure.

Namespaces do not clearly convert this into a broad container escape primitive. If AF_NFC socket creation is allowed to untrusted users in the evaluated product, PR:L is appropriate. If NFC device setup is restricted to privileged services, practical triggering may be more limited, but the bug is still a kernel UAF candidate.

Call-site confidence: medium. The changed function and state/list relationship are visible, but the full later traversal paths of `connecting_sockets` are not included in the input.

## 4. Severity interpretation

This is stronger than an ordinary Moderate correctness bug because the patch explicitly fixes a use-after-free in a kernel socket lifetime path. Realistic impact is most likely local DoS via kernel crash under specific NFC LLCP conditions. Theoretical privilege escalation is not proven, but stale references to freed socket objects are a meaningful memory-lifetime risk and should not be auto-closed.

This is best treated as Actionable Moderate at minimum. It is not a Strong Important candidate on conservative evidence because the patch does not show controlled reclaim, write-after-free, type confusion, callback control, or an arbitrary read/write primitive.

## 5. One-sentence report phrase

A use-after-free in the NFC LLCP socket release path can leave a connecting socket on the wrong list after release, allowing later kernel list processing to access freed memory and potentially cause a local kernel crash, with privilege escalation requiring manual review but not demonstrated.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED.
YES REQUIRES MANUAL CHECK.

Reason: confirmed kernel UAF and lifetime/list corruption. The known practical impact is likely DoS, but the stale freed socket reference makes this unsuitable for automatic closure without source-level review of later list traversal and reclaim behavior.

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

Patch: nfc: llcp: Fix use-after-free in llcp_sock_release() [ Upstream
Commit: 89ba026747019ee643d29407435ddc118e6ca908
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=89ba026747019ee643d29407435ddc118e6ca908

Changed files:
  net/nfc/llcp_sock.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=89ba026747019ee643d29407435ddc118e6ca908

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

The original Linux kernel CVE announcement for CVE-2026-64011 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64011

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: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: 4
  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: MODERATE
KPANIC detected for this report: YES
Published priority for this report (same as in Subject): MODERATE 7.0

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).