CVE-2026-43334
Received Received - Intake
Bluetooth SMP Security Bypass in Linux Kernel

Publication date: 2026-05-08

Last updated on: 2026-05-08

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: Bluetooth: SMP: force responder MITM requirements before building the pairing response smp_cmd_pairing_req() currently builds the pairing response from the initiator auth_req before enforcing the local BT_SECURITY_HIGH requirement. If the initiator omits SMP_AUTH_MITM, the response can also omit it even though the local side still requires MITM. tk_request() then sees an auth value without SMP_AUTH_MITM and may select JUST_CFM, making method selection inconsistent with the pairing policy the responder already enforces. When the local side requires HIGH security, first verify that MITM can be achieved from the IO capabilities and then force SMP_AUTH_MITM in the response in both rsp.auth_req and auth. This keeps the responder auth bits and later method selection aligned.
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Meta Information
Published
2026-05-08
Last Modified
2026-05-08
Generated
2026-05-09
AI Q&A
2026-05-08
EPSS Evaluated
N/A
NVD
EUVD
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-UNKNOWN
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability exists in the Linux kernel's Bluetooth Secure Simple Pairing (SMP) process. Specifically, when building the pairing response, the system does not enforce the local requirement for Man-In-The-Middle (MITM) protection before responding. If the initiator device omits the SMP_AUTH_MITM flag, the responder may also omit it, even if the local policy requires MITM protection. This leads to inconsistent method selection during pairing, potentially weakening the security of the Bluetooth connection.


How can this vulnerability impact me? :

This vulnerability can impact you by allowing a Bluetooth pairing process to proceed without the required Man-In-The-Middle (MITM) protection, even if your device's security policy demands it. This could enable an attacker to intercept or manipulate the Bluetooth pairing process, potentially compromising the confidentiality and integrity of the connection.


What immediate steps should I take to mitigate this vulnerability?

The vulnerability has been resolved in the Linux kernel by enforcing the local BT_SECURITY_HIGH requirement before building the pairing response in Bluetooth SMP. To mitigate this vulnerability, ensure your Linux kernel is updated to a version that includes this fix.

Specifically, the fix forces the responder to require MITM protection in the pairing response when the local side requires HIGH security, aligning the responder authentication bits and method selection with the pairing policy.


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