[CVE-2026-72299][MODERATE 7.0] tipc: restrict socket queue dumps in enqueue tracepoints [ Upstream

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

CVE: CVE-2026-72299
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: tipc: restrict socket queue dumps in enqueue tracepoints [ Upstream
Commit: 12876864f9de5fa6f611a30c6c17e405a773bf0a
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=12876864f9de5fa6f611a30c6c17e405a773bf0a
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72299
Analysis date: Sat, 15 Aug 2026 19:50:12 -0400
ActionableScore: 5
ActionableScore lower bound: 4
Actionable bucket: Actionable Moderate at minimum
Manual review required: NO

Summary:
TIPC enqueue tracepoints could dump sk_receive_queue without holding the lock that protects it, allowing a race with socket owner dequeue or purge operations and causing a use-after-free read of freed skbs that may crash the kernel.

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

The original Linux kernel CVE announcement for CVE-2026-72299 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72299

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: NO

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-2026-72299	MODERATE	CHECK WITH IMPACT FROM ORIG NN LOW	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H';*CWE-416;CWE-362;CWE-667;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '6.4';DESCR 'TIPC enqueue tracepoints could dump sk_receive_queue while tipc_sk_enqueue holds only the socket backlog spinlock. The backlog queue is protected in this path, but sk_receive_queue can be consumed or purged concurrently by the socket owner, so TIPC_DUMP_ALL can make tipc_skb_dump read an skb that was already dequeued or freed. This is a race condition with a use-after-free read and can lead to a KASAN report or kernel crash. For the CVSS the PR:N is used for the paranoid network-adjacent interpretation because a peer that can reach the TIPC bearer may trigger enqueue activity without local privileges on the victim when the affected tracepoints are enabled. The base local interpretation uses PR:L because a local process can more directly drive TIPC socket activity and the race timing. The issue is not a generic Internet reachable bug, but TIPC is a network protocol used in clustered or local network deployments. Impact is at least denial of service, and in the paranoid view limited confidentiality or integrity impact is kept for manual-review sensitivity because the primitive is a UAF read in a kernel networking object.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 5)	YES	KASAN TIPC SKB HARDWARE  DECREASED_TO_MODERATEREG_BASED_ON_FALSEPOSCHECKOFKP	NO	NO	checked

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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 drive TIPC socket activity and race against socket receive queue consumption if TIPC is available and the relevant tracepoints are enabled.

* Memory corruption, weak/indirect corruption candidate: +1
  KASAN reports a use-after-free read from an skb during trace dumping. This is a real stale-object dereference, but the patch does not show attacker-controlled reclaim, write-after-free, callback control, type confusion, or arbitrary write.

* Real lifetime corruption: +1
  The bug is a lifetime race between tracepoint queue traversal and concurrent dequeue/free of skbs from sk_receive_queue.

* Reliable kernel crash / strong DoS: +1
  The reported KASAN trace shows a concrete invalid access path that can lead to a kernel crash or panic depending on runtime configuration.

* Hard or unreliable race / special timing required: -1
  The issue depends on a race between enqueue trace dumping and socket owner queue consumption or purging.

* Rare/difficult-to-reach configuration: -1
  Practical exposure depends on TIPC usage and affected tracepoints being enabled. TIPC is not a default Internet-facing protocol in most deployments.

Paranoid additional interpretation:

* Network-triggerable / adjacent network influence: +1 net increase
  A TIPC peer on a configured bearer may be able to trigger enqueue activity without local privileges on the victim, but this is better treated as network-adjacent rather than generic Internet remote exposure.

Result:

* Conservative: 4
* Paranoid: 5

## 3. Reachability analysis

The most direct trigger is local TIPC socket activity combined with the affected enqueue tracepoints. A remote peer may influence the path if TIPC is configured over a reachable bearer and tracing is enabled, but this is not a generic remotely reachable TCP/IP bug. TIPC is normally used in clustered or local network environments and is not commonly exposed to the public Internet.

Namespaces and containers may matter if an untrusted workload can create or use TIPC sockets in a configured namespace, but enabling kernel tracepoints is normally privileged. If tracepoints are disabled, practical exploitability is much lower.

Call-site confidence: high. The provided trace and diff show the affected call path in tipc_sk_enqueue(), the unsafe TIPC_DUMP_ALL usage, and the restriction to TIPC_DUMP_SK_BKLGQ.

## 4. Severity interpretation

This is more than an ordinary cleanup bug because it is a real race-dependent UAF read in a kernel networking path. However, it does not reach Strong Important by default because the primitive is read-only, tracepoint-dependent, race-dependent, and lacks evidence of controlled reclaim, object replacement, write-after-free, callback control, or privilege escalation.

Realistic impact is kernel crash / DoS. Theoretical confidentiality or integrity concerns are limited and mainly justify manual review, not an Important classification by themselves.

## 5. One-sentence report phrase

TIPC enqueue tracepoints could dump sk_receive_queue without holding the lock that protects it, allowing a race with socket owner dequeue or purge operations and causing a use-after-free read of freed skbs that may crash the kernel.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Reason: this is a race-triggered UAF read in a networking subsystem with possible network-adjacent reachability when TIPC and tracing are enabled, but no demonstrated write primitive or strong LPE path is shown.

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

Patch: tipc: restrict socket queue dumps in enqueue tracepoints [ Upstream
Commit: 12876864f9de5fa6f611a30c6c17e405a773bf0a
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=12876864f9de5fa6f611a30c6c17e405a773bf0a

Changed files:
  lib/dump_stack.c
  mm/kasan/report.c
  mm/kasan/report_generic.c
  net/tipc/trace.c
  net/tipc/socket.c
  net/tipc/trace.h
  net/tipc/node.c
  net/socket.c
  fs/splice.c
  arch/x86/entry/syscall_64.c
  arch/x86/entry/entry_64.S

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=12876864f9de5fa6f611a30c6c17e405a773bf0a

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

The original Linux kernel CVE announcement for CVE-2026-72299 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72299

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:H
  The Best / paranoid CVSS vector: AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H
  The Best / paranoid CVSS score: 6.4

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: NO
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).