[CVE-2026-52917][MODERATE 7.0] sctp: diag: reject stale associations in dump_one path

[CVE-2026-52917][MODERATE 7.0] sctp: diag: reject stale associations in dump_one path

[AL-KERNEL]

CVE: CVE-2026-52917
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: sctp: diag: reject stale associations in dump_one path
Commit: 6657af827e21883ae90693e42e7f59a6aab690b5
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6657af827e21883ae90693e42e7f59a6aab690b5
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-52917
Analysis date: Wed, 24 Jun 2026 04:19:08 -0400
ActionableScore: 5
ActionableScore lower bound: 4
Actionable bucket: Strong Important candidate / Actionable Moderate at minimum
Manual review required: YES

Summary:
A race in the SCTP sock_diag dump_one path can allow stale association state to be formatted after teardown, causing an out-of-bounds read from unrelated association memory and possible local information disclosure or DoS.

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

The original Linux kernel CVE announcement for CVE-2026-52917 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-52917

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-2026-52917	MODERATE	CHECK	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:N/A:H';CWE-362;CWE-125;*CWE-416;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:L';BEST CVSS score: '6.3';DESCR 'A race in the SCTP sock_diag dump_one path can allow diagnostic reporting to continue after an association was reaped or detached from its endpoint. The code can block on lock_sock(sk) and then resume after the bind address list was freed, so inet_assoc_attr_size() or inet_diag_msg_sctpasoc_fill() may read stale association state. This can turn an empty bind address list into an out of bounds read from unrelated association memory. For the CVSS the PR:L is used because a local user or process is needed to issue SCTP sock_diag requests and race association teardown. The issue is not directly network reachable, although remote SCTP traffic may help create association churn in some environments. Impact is at least local information disclosure or denial of service, and the paranoid score treats the stale state and OOB read as a manual review candidate for stronger confidentiality impact.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 5)	YES	READ OOB NOMEMCHK UAF NETWORK LINUS KPANIC  KPANIC LOWERED_FROM_HIGH_BASED_ON_GUESSCVSS 	NO	NO	checked

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

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

* Local unprivileged trigger: +1
  SCTP sock_diag requests are a local netlink diagnostic interface. A local process can plausibly create or inspect SCTP associations and race teardown.

* Memory corruption, weak or indirect corruption candidate: +1
  The patch describes stale association state and an out-of-bounds read from unrelated association memory, but not an OOB write, arbitrary write, callback hijack, or controlled object replacement.

* Real lifetime corruption: +1
  The diagnostic path can continue after `sctp_association_free()` marked the association dead and freed the bind-address list.

* Confidentiality impact plausible: +1
  `inet_diag_msg_sctpasoc_fill()` may interpret unrelated memory as an `sctp_sockaddr_entry`, making a kernel memory disclosure through diagnostic output plausible.

* Availability impact realistic: +1 in paranoid score
  The stale/OOB read may also cause a kernel fault depending on memory layout and debug/hardening state.

* Hard race / timing window: -1 in conservative score
  Triggering requires racing exact sock_diag lookup, `lock_sock(sk)`, and association teardown. The paranoid score does not subtract this because the commit describes a concrete race window and multiple reporters suggest practical reproducibility.

No remote-reachable bonus is applied. Remote SCTP traffic may help create association churn, but the vulnerable formatting path is local sock_diag control plane, not direct packet processing.

## 3. Reachability analysis

A local user or local process can potentially trigger the bug by issuing SCTP sock_diag exact lookup requests while SCTP associations are being torn down. Full host root is not clearly required, so applying a `Requires admin/root/CAP_*` penalty would likely be too aggressive. Namespaces may matter because containers with network namespace access and SCTP enabled could reach the diagnostic path depending on policy and kernel configuration.

The path is not directly network reachable. An external peer may influence SCTP association lifetime, but exploitation still depends on local diagnostic access. SCTP is less common than TCP/UDP, but it is a standard kernel networking subsystem and should not be treated as purely rare hardware or legacy-only exposure.

## 4. Severity interpretation

This is more than an ordinary Moderate because the patch explicitly describes a stale lifetime race plus an out-of-bounds read from unrelated association memory. Realistically, the strongest demonstrated primitive is local information disclosure and possible DoS, not privilege escalation. Theoretical LPE is not strongly supported because the patch does not show attacker-controlled reclaim, writable stale object access, callback dispatch, type confusion, or refcount takeover.

Conservative handling is borderline manual-review. Paranoid handling reaches Actionable Moderate because kernel memory disclosure through sock_diag output is plausible and the lifetime bug involves freed association state.

## 5. One-sentence report phrase

A race in the SCTP sock_diag dump_one path can allow stale association state to be formatted after teardown, causing an out-of-bounds read from unrelated association memory and possible local information disclosure or DoS.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: the bug combines a race, stale lifetime state, and an OOB read in kernel networking diagnostic output, which is enough to require manual validation of the actual disclosure and crash potential.

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

Patch: sctp: diag: reject stale associations in dump_one path
Commit: 6657af827e21883ae90693e42e7f59a6aab690b5
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6657af827e21883ae90693e42e7f59a6aab690b5

Commit description:

The SCTP exact sock_diag lookup can hold a transport reference, block on
lock_sock(sk), and then resume after sctp_association_free() has marked
the association dead and freed its bind address list.

When that happens, inet_assoc_attr_size() and
inet_diag_msg_sctpasoc_fill() can still dereference association state
that is no longer valid for reporting. In particular,
inet_diag_msg_sctpasoc_fill() may read an empty bind-address list as a
real sctp_sockaddr_entry and trigger an out-of-bounds read from
unrelated association memory.

Reject the association after taking the socket lock if it has been
reaped or detached from the endpoint, and report the lookup as stale.
This keeps the exact dump-one path from formatting torn association
state.

Fixes: 8f840e4 ("sctp: add the sctp_diag.c file")
Cc: stable@kernel.org
Reported-by: Yuan Tan <yuantan098@gmail.com>
Reported-by: Yifan Wu <yifanwucs@gmail.com>
Reported-by: Juefei Pu <tomapufckgml@gmail.com>
Reported-by: Zhengchuan Liang <zcliangcn@gmail.com>
Reported-by: Xin Liu <bird@lzu.edu.cn>
Signed-off-by: Zhao Zhang <zzhan461@ucr.edu>
Signed-off-by: Ren Wei <n05ec@lzu.edu.cn>
Acked-by: Xin Long <lucien.xin@gmail.com>
Link: https://patch.msgid.link/fac6043fa20a2ff68e12958c431836f692c51268.1780113823.git.zzhan461@ucr.edu
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  net/sctp/diag.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=6657af827e21883ae90693e42e7f59a6aab690b5

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

The original Linux kernel CVE announcement for CVE-2026-52917 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-52917

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:N/A:L
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:H
  The Best / paranoid CVSS score: 6.3

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).