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CVE Record

CVE-2026-46140: Bluetooth: btmtk: validate WMT event SKB length before struct access

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: btmtk: validate WMT event SKB length before struct access btmtk_usb_hci_wmt_sync() casts the WMT event response SKB data to struct btmtk_hci_wmt_evt (7 bytes) and struct btmtk_hci_wmt_evt_funcc (9 bytes) without first checking that the SKB contains enough data. A short firmware response causes out-of-bounds reads from SKB tailroom. Use skb_pull_data() to validate and advance past the base WMT event header. For the FUNC_CTRL case, pull the additional status field bytes before accessing them.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

This is a Linux kernel Bluetooth driver bug affecting MediaTek btmtk handling. A malformed or short firmware response can make the kernel read beyond expected buffer data. Sources do not provide CVSS, confirmed impact beyond out-of-bounds read, or active exploitation evidence.

Executive priority

Treat as a targeted kernel maintenance item, not an emergency internet-wide threat. Patch affected Linux Bluetooth-capable endpoints through normal expedited kernel update channels, with higher priority for fleets relying on MediaTek Bluetooth hardware.

Technical view

btmtk_usb_hci_wmt_sync casts WMT event SKB data to 7-byte and 9-byte structures before validating sufficient length. Short firmware responses can cause out-of-bounds reads from SKB tailroom. The referenced fixes validate and advance SKB data before accessing the base header and FUNC_CTRL status fields.

Likely exposure

Exposure is likely limited to Linux systems using the MediaTek btmtk Bluetooth driver, especially USB Bluetooth hardware. This is not described as internet-facing. The CVE affected-version data is unusual and should be reconciled against distribution kernel advisories.

Exploitation context

CISA KEV is false in the provided bundle, and no cited source reports active exploitation. Exploitation would depend on causing a short WMT firmware response in the btmtk Bluetooth path. The public sources do not define practical attack prerequisites or business impact.

Researcher notes

The record lacks CVSS, CWE, and detailed impact classification. The defect is an out-of-bounds read from SKB tailroom during firmware event handling. Review the stable commits for exact affected branches and validate downstream backports rather than relying only on raw version strings.

Mitigation direction

  • Apply vendor kernel updates that include the referenced stable btmtk fixes.
  • Prioritize Linux endpoints with MediaTek Bluetooth hardware or the btmtk driver.
  • If Bluetooth is unnecessary, consider disabling it following vendor and business policy.
  • Track distribution advisories for corrected package versions and backports.

Validation and detection

  • Inventory Linux systems using MediaTek Bluetooth or the btmtk driver.
  • Check kernel package changelogs for the btmtk WMT event length validation fix.
  • Compare deployed kernels against vendor advisories and referenced stable commits.
  • Confirm no unsupported custom kernel lacks the backported validation changes.
Prepared
Confidence
medium
Sources
7

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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CVE-2026-46140 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
3Timeline events
0ADP providers
6Source links

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxf0457842215438786e2e205ad06a4fbb8ab63cd0, d019930b0049fc2648a6b279893d8ad330596e81, d019930b0049fc2648a6b279893d8ad330596e81, d019930b0049fc2648a6b279893d8ad330596e81, d019930b0049fc2648a6b279893d8ad330596e81, 6.6.142unaffected
LinuxLinux6.11, 0, 6.6.144, 6.12.88, 6.18.30, 7.0.7, 7.1affected
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.