[CVE-2026-90065][LOW] net/smc: release the internal TCP sock on IPPROTO_SMC socket creation failure [ Upstream

[CVE-2026-90065][LOW] net/smc: release the internal TCP sock on IPPROTO_SMC socket creation failure [ Upstream

[AL-KERNEL]

CVE: CVE-2026-90065
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: net/smc: release the internal TCP sock on IPPROTO_SMC socket creation failure [ Upstream
Commit: 2f4ece7fed6d915ec64b7735962c0d84d6261032
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=2f4ece7fed6d915ec64b7735962c0d84d6261032
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90065
Analysis date: Thu, 17 Sep 2026 21:31:39 -0400
ActionableScore: 2
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-90065 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90065

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: LOW
Manual review required: NO

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

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

CVE-2026-90065	LOW	https://www.kernelcve.org/list/?q=CVE-2026-90065 CHECK WITH IMPACT FROM ORIG NN LOW	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-401;*CWE-772;**CWE-400;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.5';DESCR 'A resource leak in IPPROTO_SMC socket creation can occur when proto init creates the internal TCP clcsock but a later socket create hook fails the operation. A local process can repeatedly trigger failed socket(AF_INET, SOCK_STREAM, IPPROTO_SMC) calls under a deny policy such as BPF_CGROUP_INET_SOCK_CREATE, causing one tcp_sock to be leaked per failure and potentially exhausting kernel memory over time. For the CVSS the PR:L is used because reliable triggering requires a local process with access to the SMC socket interface and a local policy path that rejects creation after init. The issue is not network reachable because it is triggered through local socket creation and cgroup BPF policy handling rather than remote packet traffic. Impact is denial of service through resource exhaustion. No confidentiality or integrity impact is assigned because the observable primitive is a memory leak without evidence of UAF, OOB access, information disclosure, or arbitrary write.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 2)	YES	BPF LEAK  INCREASED_FROM_LOW_BASED_ON_HIGHCVSSSCORE DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3	YES	NO	checked

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

ActionableScore=2
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES

1. ActionableScore

* Raw conservative score: 2
* Conservative score: 2
* Raw paranoid score: 2
* Paranoid score: 2
* Final recommended bucket: **Ordinary Moderate**::

No floor or cap changed the score.

2. Signal breakdown

Positive signals:

* +1 Concrete persistent kernel resource/reference leak. The internal TCP clcsock is created during IPPROTO_SMC socket initialization and is not released when socket creation fails after proto init.
* +1 Below-host-admin local trigger. The supplied context states that an unprivileged task able to attach a deny-all BPF_CGROUP_INET_SOCK_CREATE program to its own cgroup can repeatedly trigger failed IPPROTO_SMC socket creation.

Negative or non-awarded signals:

* +0 Real UAF. The vulnerable behavior is a leaked tcp_sock, not a stale post-free use.
* +0 Concrete repeated release/refcount. There is no first release followed by a second lifetime mutation on the same dangling reference.
* +0 Reliable kernel crash. No immediate panic or NULL dereference is established by the vulnerable path.
* +0 Extra availability. Unbounded growth supports DoS risk, but it is the consequence of the same resource leak and is not counted again as a separate signal.
* +0 Confidentiality and integrity. No information disclosure, UAF, OOB access, arbitrary write, or ownership bypass is established.
* +0 Remote reachability. The trigger is local socket creation plus local cgroup BPF policy behavior, not remote packet traffic.
* +0 Strong LPE or weak LPE. No controlled reclaim, object replacement, refcount takeover, callback influence, or privilege-escalation primitive is shown.
* +0 BPF strong control-plane escalation. BPF is involved as the failure hook, but the vulnerable primitive is still only a resource leak in SMC socket cleanup.

3. Reachability analysis

The trigger is local. The supplied context describes a task that can attach a deny-all BPF_CGROUP_INET_SOCK_CREATE program to its own cgroup and then repeatedly call socket(AF_INET, SOCK_STREAM, IPPROTO_SMC), causing the post-init creation failure.

Host-admin-equivalent privilege is not positively established as required by the supplied scenario, so HostAdminRequired=NO. The exact namespace and capability details for loading and attaching the cgroup BPF program are not fully resolved from the patch alone, so NamespaceScopedPrivilege=UNKNOWN.

There is no direct network trigger. IPPROTO_SMC is a socket protocol path, but the vulnerable operation is failed local socket creation, not packet processing. No special physical hardware is required by the evidence. No race is required. Repeated attempts are cheap once the local failure condition exists.

4. Primitive and severity interpretation

The exact primitive is a persistent kernel resource leak: one internal TCP socket object can be leaked for each failed IPPROTO_SMC socket creation after proto init has already created clcsock.

This is not active structured UAF and not fixed stale storage. The patch also unhashes the SMC socket before releasing clcsock because smc_diag can walk the hash and dereference smc->clcsock. That ordering prevents a possible unsafe observation in the new destroy path, but the original vulnerability evidenced here is a missing release, not a demonstrated UAF.

PrimitiveClass=CLASS_C because the established consequence is resource exhaustion DoS without an independently useful corruption primitive. The demonstrated consequence is kernel memory growth over repeated failures. The speculative consequence is eventual denial of service due to memory exhaustion. There is no meaningful leverage beyond resource exhaustion.

ImportantCandidate=NO because there is no memory corruption, repeated lifetime mutation, authorization bypass, COW violation, or demonstrated LPE. AutoDowngradeAllowed=YES because the issue is a pure resource leak and does not leave unresolved exploitation leverage that would be lost by ordinary Moderate handling.

5. One-sentence report phrase

A local IPPROTO_SMC socket creation failure can leak one internal TCP clcsock per failed call when a cgroup socket-create hook rejects the socket after proto init, allowing repeated local resource exhaustion but not showing memory corruption or privilege escalation.

6. Manual review recommendation

NO MANUAL CHECK NEEDED

Reason: the established primitive is a concrete resource leak with possible DoS through accumulation, but there is no UAF, repeated refcount mutation, arbitrary write, information leak, authorization bypass, or remote trigger.

7. Call-site confidence

Call-site confidence: high

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

Patch: net/smc: release the internal TCP sock on IPPROTO_SMC socket creation failure [ Upstream
Commit: 2f4ece7fed6d915ec64b7735962c0d84d6261032
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=2f4ece7fed6d915ec64b7735962c0d84d6261032

Changed files:
  net/smc/smc_inet.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=2f4ece7fed6d915ec64b7735962c0d84d6261032

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

The original Linux kernel CVE announcement for CVE-2026-90065 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90065

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:L/PR:L/UI:N/S:U/C:N/I:N/A:L
  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: unknown
  Paranoid ActionableScore: 2

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: LOW
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): LOW

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).