[CVE-2026-72242][MODERATE 7.0] selinux: avoid sk_socket dereference in selinux_sctp_bind_connect() [ Upstream

[CVE-2026-72242][MODERATE 7.0] selinux: avoid sk_socket dereference in selinux_sctp_bind_connect() [ Upstream

[AL-KERNEL]

CVE: CVE-2026-72242
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: selinux: avoid sk_socket dereference in selinux_sctp_bind_connect() [ Upstream
Commit: 5d4d93f9bfbc997ffbb03cd6107e8f6979dbb9b4
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=5d4d93f9bfbc997ffbb03cd6107e8f6979dbb9b4
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72242
Analysis date: Sun, 16 Aug 2026 08:59:46 -0400
ActionableScore: 5
ActionableScore lower bound: 4
Actionable bucket: Actionable Moderate at minimum
Manual review required: YES

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-72242 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72242

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-2026-72242	MODERATE	CHECK WITH IMPACT FROM ORIG NN MODERATE	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-476;CWE-362;CWE-754;Other CVSS 'AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '7.5';DESCR 'A NULL pointer dereference can occur in the SELinux SCTP bind connect hook because selinux_sctp_bind_connect used sk_socket when the hook is invoked from the ASCONF softirq path. In that path there is no file reference guaranteeing that sk_socket is present, so a remote SCTP peer may be able to drive the ASCONF handling path into a NULL socket dereference and crash the kernel. For the CVSS the PR:N value is used for the paranoid score because the trigger can be network reachable through SCTP packet handling and does not require a local account on the target once the vulnerable SCTP and SELinux configuration is exposed. The issue is network reachable in SCTP deployments that allow ASCONF processing, but practical exposure is limited by requiring SCTP, SELinux with the relevant policy capability, and a suitable association or protocol state. Impact is denial of service via kernel crash only, with no supported evidence of privilege escalation or information disclosure.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 5)	YES	SIMPLEFIX LINUS IPV6  KPANIC INCREASED_TO_MODERATE7_BASED_ON_GUESSCVSS	NO	NO	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
* Remote reachable / network-triggerable: +2. The affected path is SCTP ASCONF processing via `sctp_process_asconf`, so a peer may be able to reach it over the network if SCTP and ASCONF are exposed.
* Reliable kernel crash / strong DoS: +1. The bug is a NULL `sk_socket` dereference in kernel context.
* Availability impact realistic: +1. A network-triggered kernel NULL dereference can plausibly cause host-wide DoS depending on panic and oops handling.
* Common networking / packet-processing path: +1 in the paranoid score. This is a protocol receive/control path rather than a local ioctl-only path, although SCTP itself is not as broadly exposed as TCP/IP.
* Rare AND difficult-to-reach subsystem/configuration: -1. Practical exposure requires SCTP, SELinux with the relevant SCTP policy capability, ASCONF processing, and suitable association state.
* No generic memory corruption score. The patch supports NULL dereference, not UAF, OOB write, double free, type confusion, or attacker-controlled memory reuse.
* No privilege escalation score. There is no supported write primitive, reclaim primitive, callback control, or object confusion.

3. Reachability analysis
A remote SCTP peer is the relevant attacker model when SCTP ASCONF is enabled and reachable. The ordinary setsockopt callers are not affected because they hold a file reference, while the ASCONF softirq path lacks that guarantee. No local account is needed for the paranoid network-triggerable interpretation, so PR would be PR:N in CVSS terms. Containers and namespaces mainly affect whether SCTP traffic or SELinux policy exposure is reachable, but they do not create a stronger local LPE primitive from this patch. The path is not universally exposed by default because SCTP and this SELinux SCTP policy behavior must be in use.

4. Severity interpretation
This behaves like an actionable Moderate network DoS, not an Important memory-corruption vulnerability. The theoretical impact is a kernel crash through NULL dereference. The realistic evidence does not support confidentiality impact, integrity impact, or privilege escalation. Manual review is still justified because the trigger is plausibly network reachable in SCTP deployments and the failure happens in kernel networking and SELinux hook code.

5. One-sentence report phrase
A NULL pointer dereference in the SELinux SCTP bind/connect hook can be triggered from the SCTP ASCONF softirq path when `sk_socket` is absent, allowing a remote SCTP peer in affected configurations to crash the kernel.

6. Manual review recommendation
MANUAL CHECK REQUIRED.
Reason: network-reachable kernel NULL dereference in an SCTP receive/control path, although impact appears limited to DoS and deployment exposure is configuration-dependent.

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

Patch: selinux: avoid sk_socket dereference in selinux_sctp_bind_connect() [ Upstream
Commit: 5d4d93f9bfbc997ffbb03cd6107e8f6979dbb9b4
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=5d4d93f9bfbc997ffbb03cd6107e8f6979dbb9b4

Changed files:
  security/selinux/hooks.c
  security/SCTP.rst

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=5d4d93f9bfbc997ffbb03cd6107e8f6979dbb9b4

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

The original Linux kernel CVE announcement for CVE-2026-72242 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72242

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: 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).