[CVE-2026-68162][MODERATE 7.0] Revert "sctp: sysctl: auth_enable: avoid using current->nsproxy" This reverts

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

CVE: CVE-2026-68162
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: Revert "sctp: sysctl: auth_enable: avoid using current->nsproxy" This reverts
Commit: 19573dcddb8819fd68d6cd1f916c1c99c3fa4ff4
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=19573dcddb8819fd68d6cd1f916c1c99c3fa4ff4
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68162
Analysis date: Mon, 10 Aug 2026 19:17:17 -0400
ActionableScore: 5
ActionableScore lower bound: 4
Actionable bucket: Strong Important candidate / Actionable Moderate at minimum
Manual review required: YES

Summary:
An SCTP `auth_enable` sysctl lifetime race can leave an already opened per-net sysctl file able to update a destroyed SCTP control socket during network namespace teardown, creating a local UAF with reliable DoS impact and a weak but review-worthy LPE concern.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-68162 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68162

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.

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AL-KERNEL CLASSIFICATION RESULT
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CVE-2026-68162	MODERATE	CHECK WITH IMPACT FROM ORIG NN MODERATE	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-362;*CWE-672;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7';DESCR 'The SCTP auth_enable sysctl handler can update the per net SCTP control socket after the socket lifetime is no longer valid during network namespace teardown. An already opened sysctl file can still reference the per net SCTP state through ctl data while teardown is unregistering and destroying SCTP resources, which creates a race and a use after free candidate on net sctp ctl_sock. For the CVSS the PR:L is used because reliable triggering may be possible for a local user or process with delegated network namespace administration, container root, or CAP_NET_ADMIN like permissions rather than full host root. The issue is not directly network reachable because the trigger is a local sysctl and netns teardown control plane path, not SCTP packet processing. Impact is at least a local denial of service via kernel crash and in the paranoid case may allow confidentiality and integrity impact due to kernel use after free memory corruption, so privilege escalation cannot be ruled out without manual review.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 5)	YES	INIT UAF NETWORK LINUS KPANIC PACKET 	YES	NO	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=5
ActionableScoreLower=4

## 1. ActionableScore

* Conservative score: 4
* Paranoid score: 5
* Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**::

## 2. Signal breakdown

Conservative signals:

* Local namespace or local control-plane trigger: +1. The trigger is through the SCTP per-net sysctl path and network namespace teardown, not through remote SCTP packets.
* Memory corruption, weak primitive: +1. The patch and commit explicitly describe a UAF window involving `net->sctp.ctl_sock`, but no attacker-controlled reclaim or arbitrary write primitive is shown.
* Real lifetime corruption: +1. The bug is a real object lifetime mismatch where sysctl remains writable after the control socket can be destroyed.
* Reliable kernel crash or strong DoS: +1. A stale control socket access during teardown is a plausible kernel crash path.
* Cross-boundary isolation concern: +1. If reachable from a delegated network namespace or container-like environment, the issue may let a reduced-privilege context affect the host kernel.
* Hard race or teardown timing required: -1. Triggering requires an already opened sysctl file and concurrent namespace teardown.
* No full CAP penalty applied. Although writing the sysctl usually requires network-admin style privileges in the relevant namespace, this is not necessarily equivalent to full host root in container or user namespace deployments.

Paranoid additional interpretation:

* Weak LPE concern: +1. The UAF involves a freed kernel socket object and a write/update path, so privilege escalation cannot be ruled out without manual review, but there is no demonstrated reclaim, callback control, type confusion, or arbitrary write.
* Race-UAF downgrade cap applies. Conservative score is capped around 4 and paranoid score around 5 because this is a race-dependent UAF without a demonstrated exploitation primitive.

## 3. Reachability analysis

The issue is locally reachable through the SCTP `auth_enable` sysctl and network namespace teardown. It is not directly network-triggerable because incoming SCTP traffic is not the described trigger path.

Privileges depend on deployment. On a traditional host, writing the sysctl is usually restricted to an administrator or a process with network administration capability. In containerized or namespace-enabled systems, a container root or process with delegated `CAP_NET_ADMIN`-like authority in a network namespace may be a realistic trigger actor, which is weaker than full host root.

The affected path is not a common packet-processing path, but SCTP per-net sysctl handling and netns teardown are normal kernel mechanisms when SCTP and network namespaces are enabled.

## 4. Severity interpretation

This is stronger than an ordinary Moderate because it is a kernel UAF in a namespace teardown path, not merely a validation or resource leak bug. Realistic impact is most clearly local DoS via kernel crash.

Theoretical privilege escalation is plausible enough for manual review because the stale object is a kernel control socket and the vulnerable path performs an update after the socket lifetime may have ended. However, the patch does not show attacker-controlled reclaim, object replacement, callback control, type confusion, or an arbitrary write primitive. Therefore the conservative score remains Actionable Moderate rather than a clear Important.

## 5. One-sentence report phrase

An SCTP `auth_enable` sysctl lifetime race can leave an already opened per-net sysctl file able to update a destroyed SCTP control socket during network namespace teardown, creating a local UAF with reliable DoS impact and a weak but review-worthy LPE concern.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: this is a real race-dependent UAF in kernel networking namespace teardown code, with possible container or delegated namespace reachability and enough memory-lifetime risk to avoid auto-closure.

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

Patch: Revert "sctp: sysctl: auth_enable: avoid using current->nsproxy" This reverts
Commit: 19573dcddb8819fd68d6cd1f916c1c99c3fa4ff4
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=19573dcddb8819fd68d6cd1f916c1c99c3fa4ff4

Changed files:
  net/sctp/sysctl.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=19573dcddb8819fd68d6cd1f916c1c99c3fa4ff4

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

The original Linux kernel CVE announcement for CVE-2026-68162 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68162

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).