[CVE-2026-53292][MODERATE REGULAR] net: phonet: do not BUG_ON() in pn_socket_autobind() on failed bind [ Upstream

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

CVE: CVE-2026-53292
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: net: phonet: do not BUG_ON() in pn_socket_autobind() on failed bind [ Upstream
Commit: 6db58ee730bf434d1afca91b91826e26688856ed
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6db58ee730bf434d1afca91b91826e26688856ed
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53292
Analysis date: Fri, 26 Jun 2026 16:20:23 -0400
ActionableScore: 3
ActionableScore lower bound: 2
Actionable bucket: Borderline manual review recommended / Ordinary Moderate DoS
Manual review required: YES

Summary:
A local user-triggerable BUG_ON() in Phonet socket autobind can panic the kernel when `pn_socket_bind()` returns `-EINVAL` for an unbound socket in a non-`TCP_CLOSE` state, causing denial of service without evidence of memory corruption or privilege escalation.

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

The original Linux kernel CVE announcement for CVE-2026-53292 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53292

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-2026-53292	MODERATE	CHECK	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H';CWE-617;CWE-703;CWE-754;BEST CVSS score: '5.5';DESCR 'A reachable BUG_ON() in the Phonet socket autobind path can be hit when pn_socket_bind returns EINVAL because the socket state is not TCP_CLOSE while the socket still has no assigned Phonet port. A local user can trigger this through the pn_socket_sendmsg path and cause a kernel BUG or panic, resulting in denial of service. For the CVSS the PR:L is used because a local user or process must create and operate an AF_PHONET socket to reach this path. The issue is not directly network reachable and there is no supported evidence of memory corruption, information disclosure, or privilege escalation. Impact is denial of service only.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline manual review recommended / Ordinary Moderate DoS (with actual score 3)  SKIP CVE-2026-53292  SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	DANGER LINUS SYZBOT  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH	-	-	checked

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

ActionableScore=3
ActionableScoreLower=2

## 1. ActionableScore

* Conservative score: 2
* Paranoid score: 3
* Final recommended bucket: **Borderline manual review recommended / Ordinary Moderate DoS**

## 2. Signal breakdown

* Local unprivileged trigger: +1
  The crash is reachable from a user-triggerable `sendmsg()` path on an AF_PHONET socket.
* Reliable kernel crash / strong DoS: +1
  The vulnerable path reaches a `BUG_ON()` and can panic the kernel.
* Availability impact realistic: +1 in paranoid score only
  A local user-triggerable kernel panic is a real system availability impact, but this partially overlaps with the DoS signal.
* Rare AND difficult-to-reach subsystem/configuration: -1 in conservative score
  Phonet is not a broadly used default networking path on most Linux deployments.

No score added for memory corruption, UAF, OOB write, privilege escalation, information disclosure, remote reachability, or security-boundary bypass.

## 3. Reachability analysis

A local user or process can potentially trigger the issue by creating and using an AF_PHONET socket and reaching `pn_socket_sendmsg()` while the socket state causes `pn_socket_bind()` to return `-EINVAL` before a port is assigned. This does not appear to require network packet delivery from a remote host. Namespace behavior may matter only if AF_PHONET socket creation is available inside the relevant namespace, but the bug is still local rather than remote. The subsystem is relatively uncommon, so exposure is lower than for TCP/IP, netfilter, or core socket paths.

## 4. Severity interpretation

This behaves like an ordinary Moderate local denial-of-service issue, with borderline manual-review value because the crash is user-triggerable and reliable. The patch fixes a reachable assertion misuse, not a lifetime bug or memory corruption primitive. There is no evidence of confidentiality impact, integrity impact, privilege escalation, UAF, arbitrary write, or object reuse.

## 5. One-sentence report phrase

A local user-triggerable BUG_ON() in Phonet socket autobind can panic the kernel when `pn_socket_bind()` returns `-EINVAL` for an unbound socket in a non-`TCP_CLOSE` state, causing denial of service without evidence of memory corruption or privilege escalation.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Reason: the issue is a reliable local kernel panic from a syscall path, but it is not remote, not memory corruption, and affects a relatively uncommon protocol subsystem.

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

Patch: net: phonet: do not BUG_ON() in pn_socket_autobind() on failed bind [ Upstream
Commit: 6db58ee730bf434d1afca91b91826e26688856ed
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6db58ee730bf434d1afca91b91826e26688856ed

Changed files:
  net/phonet/socket.c
  net/socket.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=6db58ee730bf434d1afca91b91826e26688856ed

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

The original Linux kernel CVE announcement for CVE-2026-53292 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53292

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: Not available
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 5.5

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: 2
  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).