CVE-2026-43134

Adjacent L2CAP security bypass via undersized keys

Published May 6, 2026 · Updated May 6, 2026

Improper validation in Linux kernel Bluetooth L2CAP allows adjacent attackers to establish channels with undersized encryption keys. The l2cap_le_connect_req function accepts L2CAP_LE_CONN_REQ messages without checking the channel's encryption key size. Bluetooth proximity and an LE link are required; accepted channels expose protected service data to reading or modification.

CVSS severity8.1
High
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper validation in Linux kernel Bluetooth L2CAP allows adjacent attackers to establish channels with undersized encryption keys. The l2cap_le_connect_req function accepts L2CAP_LE_CONN_REQ messages without checking the channel's encryption key size. Bluetooth proximity and an LE link are required; accepted channels expose protected service data to reading or modification.

The record

CVE
CVE-2026-43134
Published
May 6, 2026
Updated
May 6, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
Unavailable
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 6, 2026CVE publishedPublication date reported by the CVE source.
  2. May 6, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=27e2d4c8d28be1d1b4ecfbffab572d7dbd35254d <138d7eca445ef37a0333425d269ee59900ca1104
  2. Affected versionversion=27e2d4c8d28be1d1b4ecfbffab572d7dbd35254d <335071c0c3637064ec250481f589075db44fe4e6
  3. Affected versionversion=27e2d4c8d28be1d1b4ecfbffab572d7dbd35254d <481ea39b342c347b6ac029f3d418486280be4e45
  4. Affected versionversion=27e2d4c8d28be1d1b4ecfbffab572d7dbd35254d <8dd43f9a9323f9c01bc8246da8d81a4c783c9e97
  5. Affected versionversion=27e2d4c8d28be1d1b4ecfbffab572d7dbd35254d <9118601ff90b79e8df3c0c98f48ae00c1b02ecef
  6. Affected versionversion=27e2d4c8d28be1d1b4ecfbffab572d7dbd35254d <96581749c7c14fbec32c35728520867929600041
  7. Affected versionversion=27e2d4c8d28be1d1b4ecfbffab572d7dbd35254d <ec91078e132179b04e0c3906b599816c056ceaad
  8. Affected versionversion=27e2d4c8d28be1d1b4ecfbffab572d7dbd35254d <fa6ad76fa8623c0a50d529cd5726fa5d819a3be4
  9. Affected versionversion=3.14

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=27e2d4c8d28be1d1b4ecfbffab572d7dbd35254d <138d7eca445ef37a0333425d269ee59900ca1104; version=27e2d4c8d28be1d1b4ecfbffab572d7dbd35254d <335071c0c3637064ec250481f589075db44fe4e6; version=27e2d4c8d28be1d1b4ecfbffab572d7dbd35254d <481ea39b342c347b6ac029f3d418486280be4e45; version=27e2d4c8d28be1d1b4ecfbffab572d7dbd35254d <8dd43f9a9323f9c01bc8246da8d81a4c783c9e97; version=27e2d4c8d28be1d1b4ecfbffab572d7dbd35254d <9118601ff90b79e8df3c0c98f48ae00c1b02ecef; version=27e2d4c8d28be1d1b4ecfbffab572d7dbd35254d <96581749c7c14fbec32c35728520867929600041; version=27e2d4c8d28be1d1b4ecfbffab572d7dbd35254d <ec91078e132179b04e0c3906b599816c056ceaad; version=27e2d4c8d28be1d1b4ecfbffab572d7dbd35254d <fa6ad76fa8623c0a50d529cd5726fa5d819a3be4; version=3.14

Published CVSS scores

8.1Linux Kernel CNACVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

No sourced classifications are available.

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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