[CVE-2026-43330][MODERATE REGULAR] crypto: caam - fix overflow on long hmac keys [ Upstream

[CVE-2026-43330][MODERATE REGULAR] crypto: caam - fix overflow on long hmac keys [ Upstream

[AL-KERNEL]

CVE: CVE-2026-43330
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: crypto: caam - fix overflow on long hmac keys [ Upstream
Commit: 31022cfde5235c45fa765f0aabeff5f0652852f2
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=31022cfde5235c45fa765f0aabeff5f0652852f2
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-43330
Analysis date: Thu, 21 May 2026 07:25:04 -0400
ActionableScore: 4
ActionableScore lower bound: 3
Actionable bucket: Borderline, manual review recommended
Manual review required: YES

Summary:
A local out of bounds read in the CAAM HMAC setkey path can occur when a long key is copied using a DMA aligned length instead of the real key length, with impact limited to a constrained kernel overread or possible DoS on CAAM enabled systems.

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

The original Linux kernel CVE announcement for CVE-2026-43330 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-43330

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-2026-43330	MODERATE	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:L/I:N/A:H';CWE-126;CWE-125;CWE-119;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '6.1';DESCR 'A local out of bounds read can occur in the CAAM HMAC setkey path when a long key is copied with a DMA aligned length instead of the real key length. The source key buffer has only keylen bytes, but kmemdup was asked to read aligned_len bytes, so adjacent kernel memory may be read into a temporary driver buffer. For the CVSS the PR:L is used because a local process may be able to reach the crypto setkey path through the kernel crypto API or AF_ALG when the CAAM algorithm is available. The issue is not network reachable and depends on CAAM hardware and driver configuration. Impact is mainly local denial of service or a weak confidentiality concern from an overread, but the patch does not show an attacker controlled write, UAF reclaim, or reliable privilege escalation primitive.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline, manual review recommended (with actual score 4) 	MAYBE	SIMPLEFIX DMAorINTERRUPT LINUS  INCREASED_FROM_LOW_BASED_ON_REQUIREMANUALCHECK DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	-	-	checked

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

ActionableScore=4
ActionableScoreLower=3

## 1. ActionableScore

* Conservative score: 3
* Paranoid score: 4
* Final recommended bucket: **Borderline, manual review recommended**::

## 2. Signal breakdown

* Local unprivileged trigger: +1
  The path may be reachable by a local process through the kernel crypto API or AF_ALG if the CAAM HMAC algorithm is registered and accessible.

* Local unprivileged high-control kernel data-plane API: +1
  AF_ALG and crypto setkey operations can give local users control over key length and key contents.

* Privileged kernel/device-management memory safety path: +1
  The bug is in a hardware crypto driver and involves DMA alignment handling in a trusted kernel driver path.

* Confidentiality impact plausible: +1 paranoid only
  `kmemdup(key, aligned_len)` reads beyond the provided `keylen` source buffer. This is a kernel overread, but the patch does not show a reliable user-visible disclosure path.

* Availability impact possible: +1 paranoid only
  The overread may trigger KASAN reports or faults in unlucky layouts, but a reliable production kernel crash is not strongly demonstrated.

* Rare hardware/configuration dependency: -1
  The affected path requires CAAM hardware and the relevant CAAM crypto driver and algorithm configuration.

* Constrained primitive: -1
  The primitive is a short read past the end of a source key buffer by DMA alignment padding size. There is no attacker-controlled overwrite target, UAF reclaim, arbitrary write, or page-cache corruption.

## 3. Reachability analysis

The likely attacker is a local user or local process able to request an HMAC operation using the CAAM-backed ahash implementation. In common deployments this depends on whether CAAM hardware exists, whether the driver is enabled, and whether the algorithm is exposed through AF_ALG or another local crypto API user path. Namespaces do not materially improve reachability unless the crypto interface is available inside the container. The issue is not network reachable by itself.

## 4. Severity interpretation

This behaves like a constrained local kernel overread in a hardware crypto driver, not like a strong memory corruption or privilege escalation primitive. The theoretical concern is that adjacent kernel memory is copied into a temporary buffer, but the patch does not demonstrate a reliable information leak, attacker-controlled write, UAF, or LPE path. This is therefore best treated as Borderline or low Actionable Moderate for manual review, not as a Strong Important candidate.

## 5. One-sentence report phrase

A local out of bounds read in the CAAM HMAC setkey path can occur when a long key is copied using a DMA aligned length instead of the real key length, with impact limited to a constrained kernel overread or possible DoS on CAAM enabled systems.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED.

This is a memory safety issue in a DMA-adjacent crypto driver path, but the primitive is read-only and constrained, with no demonstrated disclosure channel or privilege escalation path.

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

Patch: crypto: caam - fix overflow on long hmac keys [ Upstream
Commit: 31022cfde5235c45fa765f0aabeff5f0652852f2
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=31022cfde5235c45fa765f0aabeff5f0652852f2

Changed files:
  drivers/crypto/caam/caamalg_qi2.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=31022cfde5235c45fa765f0aabeff5f0652852f2

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

The original Linux kernel CVE announcement for CVE-2026-43330 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-43330

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:L/I:N/A:H
  The Best / paranoid CVSS score: 6.1

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: 3
  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).