[CVE-2026-46291][MODERATE REGULAR] crypto: caam - guard HMAC key hex dumps in hash_digest_key [ Upstream

[CVE-2026-46291][MODERATE REGULAR] crypto: caam - guard HMAC key hex dumps in hash_digest_key [ Upstream

[AL-KERNEL]

CVE: CVE-2026-46291
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: crypto: caam - guard HMAC key hex dumps in hash_digest_key [ Upstream
Commit: 2adbfca7452eeac45117b8e803288a2767f7075f
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=2adbfca7452eeac45117b8e803288a2767f7075f
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46291
Analysis date: Mon, 08 Jun 2026 15:27:27 -0400
ActionableScore: 4
ActionableScore lower bound: 1
Actionable bucket: Borderline, manual review recommended
Manual review required: YES

Summary:
CAAM HMAC key material could be exposed through dynamic debug hex dumps when CONFIG_DYNAMIC_DEBUG and the affected callsites are enabled, allowing a local log reader to recover secrets and potentially compromise data integrity protected by those keys.

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

The original Linux kernel CVE announcement for CVE-2026-46291 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46291

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
======================================================================

CVE-2026-46291	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:H/A:N';CWE-532;*CWE-200;CWE-312;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:N';BEST CVSS score: '6.3';DESCR 'CAAM HMAC handling could expose sensitive key material because hash_digest_key used print_hex_dump_debug for input key bytes and digested key bytes. When CONFIG_DYNAMIC_DEBUG is enabled and the relevant debug callsites are turned on at runtime, these values may be written to kernel debug logs. A local attacker who can read the affected logs could recover HMAC key material and may compromise confidentiality and integrity of data or protocols protected by that key. For the CVSS the PR:L is used for the paranoid view because the attacker may only need low privileged local log access if dynamic debug was already enabled by an administrator or by system policy. The issue is not directly network reachable. Practical exposure depends on CAAM hardware, HMAC use, dynamic debug configuration, and kernel log access policy.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline, manual review recommended (with actual score 3) 	MAYBE	SIMPLEFIX LEAK LINUS  INCREASED_FROM_LOW_BASED_ON_REQUIREMANUALCHECK DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	-	-	checked

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

ActionableScore=4
ActionableScoreLower=1

## 1. ActionableScore

* Conservative score: 1
* Paranoid score: 4
* Final recommended bucket: **Borderline, manual review recommended**::

## 2. Signal breakdown

Paranoid score signals:

* Sensitive secret exposure primitive: +2
  HMAC key bytes and digested key bytes could be dumped to kernel logs when dynamic debug is enabled for the affected CAAM callsites.

* Confidentiality impact plausible: +1
  A local attacker with access to the relevant kernel debug logs could recover HMAC key material.

* Integrity impact plausible: +1
  If the leaked HMAC key protects integrity-sensitive data or protocol messages, disclosure may allow MAC forgery or integrity bypass.

* Rare and configuration-dependent exposure: -1
  Practical exposure requires CAAM hardware, use of the affected HMAC paths, CONFIG_DYNAMIC_DEBUG, enabled debug callsites, and access to kernel logs.

* Local low-privileged log-reader scenario: +1
  In the paranoid interpretation, dynamic debug may already be enabled by an administrator or system policy, leaving only local log access as the attacker requirement.

Conservative score signals:

* Confidentiality impact plausible: +1
* Integrity impact plausible: +1
* Requires admin or privileged configuration in typical deployments: -2
* Rare and configuration-dependent exposure: -1
* Sensitive key material exposure concern: +2

Net conservative result is approximately 1 because reliable triggering normally depends on privileged debug configuration and log access policy.

## 3. Reachability analysis

This is not network reachable. The affected path is in the CAAM crypto driver HMAC key digest handling and only leaks data through debug hex dumps. In typical deployments, enabling dynamic debug for these callsites and reading kernel logs requires elevated privileges. A more concerning case exists if CONFIG_DYNAMIC_DEBUG is enabled and the relevant debug callsites are already active, while a lower-privileged local user can read the logs. Containers and namespaces usually do not help unless kernel log access or crypto device use is delegated into the container.

## 4. Severity interpretation

This behaves like an information disclosure of cryptographic secret material, not memory corruption and not DoS. There is no UAF, OOB write, arbitrary write, or privilege-escalation primitive in the patch. The practical risk is configuration-dependent, but leaked HMAC key material can be security-relevant enough to avoid automatic closure without review.

## 5. One-sentence report phrase

CAAM HMAC key material could be exposed through dynamic debug hex dumps when CONFIG_DYNAMIC_DEBUG and the affected callsites are enabled, allowing a local log reader to recover secrets and potentially compromise data integrity protected by those keys.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Reason: this is not an Important-class memory corruption issue, but it involves cryptographic key exposure and depends heavily on deployment-specific debug and log-access policy, so it should not be blindly auto-closed.

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

Patch: crypto: caam - guard HMAC key hex dumps in hash_digest_key [ Upstream
Commit: 2adbfca7452eeac45117b8e803288a2767f7075f
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=2adbfca7452eeac45117b8e803288a2767f7075f

Changed files:
  drivers/crypto/caam/caamalg_qi2.c
  drivers/crypto/caam/caamhash.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=2adbfca7452eeac45117b8e803288a2767f7075f

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

The original Linux kernel CVE announcement for CVE-2026-46291 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46291

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:H/A:N
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
  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: 1
  Paranoid ActionableScore: 4

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).