[CVE-2026-64573][MODERATE 7.0] Bluetooth: qca: fix NVM tag length underflow in TLV parser [ Upstream

[CVE-2026-64573][MODERATE 7.0] Bluetooth: qca: fix NVM tag length underflow in TLV parser [ Upstream

[AL-KERNEL]

CVE: CVE-2026-64573
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: Bluetooth: qca: fix NVM tag length underflow in TLV parser [ Upstream
Commit: 70354dbb5f72d9a76da7b031de3cbaf6c7d8fc24
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=70354dbb5f72d9a76da7b031de3cbaf6c7d8fc24
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64573
Analysis date: Wed, 05 Aug 2026 05:13:35 -0400
ActionableScore: 6
ActionableScore lower bound: 4
Actionable bucket: Actionable Moderate at minimum
Manual review required: YES

Summary:
A signed length underflow in the Bluetooth QCA NVM TLV parser can make the kernel parse past a vmalloc firmware buffer during device power-on, causing a crash and potentially limited kernel memory corruption if malformed firmware is supplied.

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

The original Linux kernel CVE announcement for CVE-2026-64573 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64573

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-2026-64573	MODERATE	CHECK WITH IMPACT FROM ORIG NN LOW	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:H';CWE-191;CWE-125;*CWE-787;*CWE-20;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7';DESCR 'A bounds check bug in the Bluetooth qca NVM TLV parser can underflow when a firmware supplied length is smaller than the NVM record size. This makes the parser iterate past the end of the vmalloc firmware buffer and can cause an out of bounds read, with possible out of bounds writes in tag handlers. For the CVSS the PR:L is used for the paranoid score because a local user or service may be able to trigger Bluetooth power on and firmware parsing once a malformed firmware image is present, although installing that image is normally privileged. The issue is not directly network reachable over Bluetooth or IP. Impact is at least local denial of service via kernel crash, and in worst case may allow confidentiality or integrity impact due to kernel memory corruption, so it should be reviewed manually.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 5)  SKIP CVE-2026-64573 UNKNOWN SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	READ KASAN OOB  KPANIC INCREASED_TO_MODERATE_FROM_LOW_BASED_ON_GUESSCVSS	-	-	checked

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

ActionableScore=6
ActionableScoreLower=4

## 1. ActionableScore

* Conservative score: 4
* Paranoid score: 6
* Final recommended bucket: **Actionable Moderate at minimum**::

## 2. Signal breakdown

Conservative scoring:

* Firmware-mediated external influence: +1
  The malformed TLV length comes from firmware data parsed by the kernel driver.
* Memory corruption, weak or constrained candidate: +1
  KASAN confirms vmalloc out-of-bounds read. The commit also states that EDL_TAG_ID handlers can write past the buffer, but target and payload control are not fully demonstrated.
* Reliable kernel crash / strong DoS: +1
  The provided trace shows a KASAN vmalloc-out-of-bounds during hci_power_on.
* Privileged kernel/device-management memory corruption path: +1
  The bug is in Bluetooth firmware parsing during QCA controller setup.
* Broad/common subsystem exposure: +1
  Bluetooth is common, though this path is QCA-specific.
* Requires admin/root in typical deployments: -2
  Installing or replacing malformed firmware is normally privileged.

Paranoid additions:

* Local unprivileged trigger after precondition: +1
  Once malformed firmware is present, a local user or service may be able to trigger Bluetooth power-on and firmware parsing depending on system policy.
* Stronger memory corruption interpretation: +1 additional over conservative
  The possible out-of-bounds write in tag handlers makes this more than a pure read-only OOB crash candidate.
* Confidentiality impact plausible: +1
  OOB reads in kernel firmware buffers create at least a weak confidentiality concern, although no direct disclosure path is shown.
* Integrity impact plausible: +1
  Possible OOB writes make integrity impact technically plausible, but not proven as controlled corruption.
* Constrained or uncertain primitive: -1
  The patch does not show attacker-controlled overwrite target, reclaim, callback control, or arbitrary write.

Result: conservative 4, paranoid 6.

## 3. Reachability analysis

The primary realistic trigger requires a malformed QCA Bluetooth firmware or NVM TLV image to be present on the system. In normal deployments, modifying firmware files under the firmware search path requires root or equivalent administrative privileges. However, after such a malformed image exists, firmware parsing occurs during Bluetooth device power-on, and some systems allow non-root desktop users or services to trigger Bluetooth enablement.

This is not directly reachable over Bluetooth or IP traffic. The external influence is firmware-mediated rather than network-triggered. Containers generally do not lower the privilege requirement unless they are allowed to control host Bluetooth devices or firmware paths, which is uncommon.

Call-site confidence: medium. The trace shows the qca_download_firmware -> qca_uart_setup -> hci_power_on path, but the exact write behavior of all EDL_TAG_ID handlers is not fully shown in the supplied diff.

## 4. Severity interpretation

This is stronger than an ordinary Moderate because it is an integer underflow in a kernel firmware parser with confirmed vmalloc out-of-bounds access and possible out-of-bounds writes. Realistic exploitation is limited by the firmware replacement precondition, so the conservative score stays borderline/manual-review level.

The paranoid score is Actionable Moderate because the bug class includes kernel OOB access in a privileged device-management path, and the commit explicitly mentions possible writes past the buffer. There is not enough evidence to call this a strong Important candidate, because no controlled overwrite, object replacement, privilege escalation path, or remote trigger is demonstrated.

## 5. One-sentence report phrase

A signed length underflow in the Bluetooth QCA NVM TLV parser can make the kernel parse past a vmalloc firmware buffer during device power-on, causing a crash and potentially limited kernel memory corruption if malformed firmware is supplied.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: confirmed kernel OOB read plus possible OOB write in firmware parsing. The realistic trigger is constrained by firmware installation privileges, but the memory-corruption class and device-management context should not be auto-closed.

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

Patch: Bluetooth: qca: fix NVM tag length underflow in TLV parser [ Upstream
Commit: 70354dbb5f72d9a76da7b031de3cbaf6c7d8fc24
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=70354dbb5f72d9a76da7b031de3cbaf6c7d8fc24

Changed files:
  drivers/bluetooth/btqca.c
  mm/kasan/report.c
  drivers/bluetooth/hci_qca.c
  drivers/bluetooth/hci_ldisc.c
  net/bluetooth/hci_sync.c
  net/bluetooth/hci_core.c
  kernel/workqueue.c
  kernel/kthread.c
  arch/x86/kernel/process.c
  arch/x86/entry/entry_64.S

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=70354dbb5f72d9a76da7b031de3cbaf6c7d8fc24

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

The original Linux kernel CVE announcement for CVE-2026-64573 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64573

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:L/I:L/A:H
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 7

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: 6

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).