[CVE-2026-52972][IMPORTANT] crypto: af_alg - Cap AEAD AD length to 0x80000000

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

CVE: CVE-2026-52972
Priority: IMPORTANT
AL-KERNEL base severity: IMPORTANT
KPANIC flag: YES
Patch: crypto: af_alg - Cap AEAD AD length to 0x80000000
Commit: f8a5203596797f394ff3f9aa4005597a92249802
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f8a5203596797f394ff3f9aa4005597a92249802
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-52972
Analysis date: Fri, 26 Jun 2026 15:51:31 -0400
ActionableScore: 7
ActionableScore lower bound: 5
Actionable bucket: Strong Important candidate / Actionable Moderate at minimum
Manual review required: YES

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-52972 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-52972

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: IMPORTANT
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-2026-52972	IMPORTANT	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:H/I:H/A:H';CWE-190;*CWE-20;*CWE-787;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7.8';DESCR 'An integer overflow risk exists in the AF_ALG AEAD control path because a user supplied associated data length from ALG_SET_AEAD_ASSOCLEN was accepted as a full u32 value. Very large values can overflow arithmetic used for TX buffer size validation, which can make later AEAD send processing operate with inconsistent length checks. For the CVSS the PR:L because triggering requires local code execution able to create and use AF_ALG sockets, but no administrative capability is normally required for this socket interface. The issue is not network reachable. Impact is at least local denial of service and the overflow class makes memory corruption impact plausible enough for manual review.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 7) 	MAYBE	SIMPLEFIX LINUS  KPANIC INCREASED_TO_MODERATE_FROM_LOW_BASED_ON_GUESSCVSS KPANIC INCREASED_TO_HIGH_BASED_ON_ACTIONABLESCOREHIGHEREQTHAN7	-	-	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=7
ActionableScoreLower=5

1. ActionableScore
* Conservative score: 5
* Paranoid score: 7
* Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**::

2. Signal breakdown
* Local unprivileged trigger: +1. AF_ALG is a local socket API and normally does not require administrative privileges.
* Local unprivileged high-control kernel data-plane API: +1. AF_ALG lets local users shape crypto requests, control messages, lengths, and buffer layout.
* Memory corruption, weak or indirect corruption candidate: +1. The patch explicitly prevents arithmetic overflows in TX buffer size checks, which can lead to inconsistent length accounting before later AEAD processing.
* Reliable kernel crash or strong DoS plausible: +1. A failed TX buffer size check can plausibly lead to kernel-side invalid buffer handling or crash.
* Broad local kernel interface exposure: +1. AF_ALG is a standard kernel crypto interface and is not a rare hardware-only path.
* Weak LPE concern in paranoid score: +1. The primitive is not demonstrated, but local user-controlled length overflow in a high-control kernel buffer path is enough to require privilege-escalation review.
* Confidentiality impact plausible in paranoid score: +1. If the overflow leads to memory corruption or inconsistent buffer processing, limited or high confidentiality impact cannot be excluded without manual analysis.
* Integrity impact plausible in paranoid score: +1. If TX buffer accounting can be bypassed, kernel memory or crypto request state corruption is technically plausible.
* No remote/network score. This is not a network-reachable protocol path.
* No admin penalty. Triggering AF_ALG sockets does not normally require CAP_SYS_ADMIN or CAP_NET_ADMIN.

3. Reachability analysis
A local unprivileged process can likely trigger the affected path by using AF_ALG AEAD sockets and setting ALG_SET_AEAD_ASSOCLEN through a control message. Containers may matter because AF_ALG availability depends on kernel configuration, module policy, seccomp, LSM, and whether the socket family is blocked, but the interface itself is not inherently root-only. The path is not remotely reachable. Realistic exploitation requires local code execution and an enabled AF_ALG AEAD configuration, but the attacker has meaningful control over length values and request layout.

4. Severity interpretation
This is stronger than an ordinary Moderate because the commit explicitly references arithmetic overflow in a kernel TX buffer size check, not only a warning or resource leak. The conservative interpretation is Actionable Moderate because the demonstrated evidence is a local integer-overflow validation bug with plausible crash impact. The paranoid interpretation is a Strong Important candidate because AF_ALG is a high-control local kernel API and length-accounting overflows can become memory-corruption or privilege-escalation primitives, even though no arbitrary write or working LPE primitive is demonstrated by the patch alone.

5. One-sentence report phrase
A local AF_ALG AEAD user can provide an oversized associated data length that may overflow TX buffer size validation, making kernel crash and possible memory corruption impact plausible and requiring manual review.

6. Manual review recommendation
MANUAL CHECK REQUIRED. The bug is a local high-control kernel API integer overflow in buffer size validation, and the patch context supports at least Actionable Moderate handling with a defensible paranoid Important-candidate score.

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UPSTREAM PATCH SUMMARY
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Patch: crypto: af_alg - Cap AEAD AD length to 0x80000000
Commit: f8a5203596797f394ff3f9aa4005597a92249802
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f8a5203596797f394ff3f9aa4005597a92249802

Commit description:

In order to prevent arithmetic overflows when checking the TX
buffer size, cap the associated data length to 0x80000000.

Reported-by: Yiming Qian <yimingqian591@gmail.com>
Fixes: 400c40c ("crypto: algif - add AEAD support")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  crypto/af_alg.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=f8a5203596797f394ff3f9aa4005597a92249802

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

The original Linux kernel CVE announcement for CVE-2026-52972 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-52972

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:L/I:L/A:H
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 7.8

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: 5
  Paranoid ActionableScore: 7

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: IMPORTANT
KPANIC detected for this report: YES
Published priority for this report (same as in Subject): IMPORTANT

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).