CVE-2025-39889

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

Bluetooth: l2cap: Check encryption key size on incoming connection

This is required for passing GAP/SEC/SEM/BI-04-C PTS test case:

Security Mode 4 Level 4, Responder - Invalid Encryption Key Size

- 128 bit

This tests the security key with size from 1 to 15 bytes while the

Security Mode 4 Level 4 requests 16 bytes key size.

Currently PTS fails with the following logs:

- expected:Connection Response:

Code: [3 (0x03)] Code

Identifier: (lt)WildCard: Exists(gt)

Length: [8 (0x0008)]

Destination CID: (lt)WildCard: Exists(gt)

Source CID: [64 (0x0040)]

Result: [3 (0x0003)] Connection refused - Security block

Status: (lt)WildCard: Exists(gt),

but received:Connection Response:

Code: [3 (0x03)] Code

Identifier: [1 (0x01)]

Length: [8 (0x0008)]

Destination CID: [64 (0x0040)]

Source CID: [64 (0x0040)]

Result: [0 (0x0000)] Connection Successful

Status: [0 (0x0000)] No fur

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References