[CVE-2026-64316][MODERATE REGULAR] crypto: caam - use print_hex_dump_devel to guard key hex dumps

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

CVE: CVE-2026-64316
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: crypto: caam - use print_hex_dump_devel to guard key hex dumps
Commit: 45c0e3615e5bca5f1fc93357af8d19975c092d4f
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=45c0e3615e5bca5f1fc93357af8d19975c092d4f
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64316
Analysis date: Sat, 25 Jul 2026 15:09:26 -0400
ActionableScore: 3
ActionableScore lower bound: 1
Actionable bucket: Borderline manual review recommended / not auto-close if CAAM dynamic debug is in scope
Manual review required: YES

Summary:
The CAAM crypto driver could leak raw cryptographic key material to kernel logs through dynamic debug hex dumps in setkey and split-key paths when CONFIG_DYNAMIC_DEBUG and the relevant debug sites are enabled.

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

The original Linux kernel CVE announcement for CVE-2026-64316 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64316

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 REGULAR
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-2026-64316	MODERATE	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:H/I:N/A:N';CWE-532;*CWE-200;CWE-312;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:N/A:N';BEST CVSS score: '5.5';DESCR 'The CAAM crypto driver could expose sensitive key material because several setkey and split key paths used print_hex_dump_debug for raw key buffers. When CONFIG_DYNAMIC_DEBUG is enabled and the relevant debug sites are active, these key bytes may be written to kernel logs during normal cryptographic key setup. For the CVSS the PR:L is used for the paranoid score because a local user or service may be able to read kernel logs or trigger key setup in some deployments where dynamic debug output was already enabled by an administrator. The issue is not directly network reachable. Impact is confidentiality loss of cryptographic secrets, with no evidence of memory corruption, denial of service, or privilege escalation.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline manual review recommended / not auto-close if CAAM dynamic debug is in scope (with actual score 2)	YES	SIMPLEFIX LEAK HARDWARE LINUS MEMORY  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	YES	NO	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=3
ActionableScoreLower=1

## 1. ActionableScore

* Conservative score: 1
* Paranoid score: 3
* Final recommended bucket: **Borderline manual review recommended / not auto-close if CAAM dynamic debug is in scope**

## 2. Signal breakdown

Conservative signals:

* Confidentiality impact plausible: +1. The patch prevents raw CAAM crypto keys from being dumped through debug hex dumps.
* Requires admin/root/CAP in typical deployments: -2. Enabling dynamic debug sites and reading unrestricted kernel logs usually requires elevated privileges.
* Rare AND difficult-to-reach subsystem/configuration: -1. Practical exposure depends on CAAM hardware, affected algorithms, CONFIG_DYNAMIC_DEBUG, and active debug configuration.
* Sensitive secret exposure floor: +3 effective practical adjustment. Even though configuration gated, the leaked object is cryptographic key material, so the issue should not be treated as a trivial log cleanup.

Paranoid signals:

* Local unprivileged trigger: +1. In some deployments a local user or service may be able to trigger crypto key setup through kernel crypto consumers while debug output was already enabled by an administrator.
* Security-sensitive secret exposure: +2. The affected data is raw cryptographic key material, not ordinary diagnostic metadata.
* Confidentiality impact plausible: +1. Kernel logs could contain usable secrets.
* Legacy / non-default execution mode: -1. The leak requires CONFIG_DYNAMIC_DEBUG and enabled debug sites.
* No memory corruption: +0. No UAF, OOB write, refcount misuse, arbitrary write, or crash primitive is shown.
* No availability or integrity signal: +0. The patch only changes debug dump gating.

Call-site confidence: high. The patch directly modifies setkey and split-key paths that receive or derive key buffers.

## 3. Reachability analysis

The bug is local/configuration-dependent rather than remotely reachable. A realistic trigger requires CAAM crypto code to process keys while CONFIG_DYNAMIC_DEBUG is enabled and the relevant debug sites are active. Reading the resulting logs is usually restricted, but some systems expose kernel logs to service accounts, operators, crash collectors, or less privileged local users. Containers generally do not lower the trigger requirement unless they can use a crypto path that reaches CAAM and can also read host kernel logs, which is uncommon.

## 4. Severity interpretation

This behaves like an information disclosure issue, not memory corruption. The realistic risk is leakage of cryptographic key material into kernel logs under debug-enabled configurations. It is not an Important-class kernel memory-safety vulnerability because there is no privilege escalation, crash, arbitrary write, UAF, or remote packet-triggered path. However, because the exposed data is sensitive key material, the paranoid practical score reaches the manual-review range.

## 5. One-sentence report phrase

The CAAM crypto driver could leak raw cryptographic key material to kernel logs through dynamic debug hex dumps in setkey and split-key paths when CONFIG_DYNAMIC_DEBUG and the relevant debug sites are enabled.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Manual review is recommended to confirm whether the affected product enables CONFIG_DYNAMIC_DEBUG, ships CAAM hardware support, allows the relevant debug sites to be enabled, and exposes kernel logs to non-admin users or service accounts.

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

Patch: crypto: caam - use print_hex_dump_devel to guard key hex dumps
Commit: 45c0e3615e5bca5f1fc93357af8d19975c092d4f
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=45c0e3615e5bca5f1fc93357af8d19975c092d4f

Commit description:

Use print_hex_dump_devel() for dumping sensitive key material in
*_setkey() and gen_split_key() to avoid leaking secrets at runtime when
CONFIG_DYNAMIC_DEBUG is enabled.

Fixes: 6e00550 ("crypto: caam - print debug messages at debug level")
Cc: stable@vger.kernel.org
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/crypto/caam/caamalg.c
  drivers/crypto/caam/caamalg_qi.c
  drivers/crypto/caam/caamhash.c
  drivers/crypto/caam/key_gen.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=45c0e3615e5bca5f1fc93357af8d19975c092d4f

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

The original Linux kernel CVE announcement for CVE-2026-64316 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64316

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:H/UI:N/S:U/C:H/I:N/A:N
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
  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: 1
  Paranoid ActionableScore: 3

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: NO
Published priority for this report (same as in Subject): MODERATE REGULAR

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).