CVE-2025-39889

Bluetooth: l2cap: Check encryption key size on incoming connection

MEDIUM
5.5
CVSS Score
Published: September 24, 2025 at 11:02 AM UTC
Updated: September 26, 2026 at 12:27 AM UTC
1 product affected across 1 vendorLinux Kernel

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Severity
MEDIUM5.5
Exploit prediction
EPSS 0.1%
SSVC
No known exploit

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 further information available And HCI logs: < HCI Command: Read Encrypti.. (0x05|0x0008) plen 2 Handle: 14 Address: 00:1B:DC:F2:24:10 (Vencer Co., Ltd.) > HCI Event: Command Complete (0x0e) plen 7 Read Encryption Key Size (0x05|0x0008) ncmd 1 Status: Success (0x00) Handle: 14 Address: 00:1B:DC:F2:24:10 (Vencer Co., Ltd.) Key size: 7 > ACL Data RX: Handle 14 flags 0x02 dlen 12 L2CAP: Connection Request (0x02) ident 1 len 4 PSM: 4097 (0x1001) Source CID: 64 < ACL Data TX: Handle 14 flags 0x00 dlen 16 L2CAP: Connection Response (0x03) ident 1 len 8 Destination CID: 64 Source CID: 64 Result: Connection successful (0x0000) Status: No further information available (0x0000)

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

5.11 ≤ v < 5.15.1815.11 ≤ v < 6.1.1355.11 ≤ v < 6.12.255.11 ≤ v < 6.14.45.11 ≤ v < 6.155.11 ≤ v < 6.6.885.16 ≤ v < 6.1.1356.13 ≤ v < 6.14.46.2 ≤ v < 6.6.886.7 ≤ v < 6.12.25288c06973daae4637f25a0d1bdaf65fdbf8455f94f911a538e089cce808a15dc3277250f4f8daef96.15 rc16.15 rc2
Vendor states this is fixed in 24b2cdfc16e9bd6ab3d03b8e01c590755bd3141f (fixed)
Vendor states this is fixed in 522e9ed157e3c21b4dd623c79967f72c21e45b78 (fixed)
Vendor states this is fixed in 9e3114958d87ea88383cbbf38c89e04b8ea1bce5 (fixed)
Vendor states this is fixed in c6d527bbd3d3896375079f5dbc8b7f96734a3ba5 (fixed)
Vendor states this is fixed in d49798ecd26e0ee7995a7fc1e90ca5cd9b4402d6 (fixed)
Vendor states this is fixed in d4ca2fd218caafbf50e3343ba1260c6a23b5676a (fixed)
Vendor states this is fixed in ed503d340a501e414114ddc614a3aae4f6e9eae2 (fixed)
Vendor states this is fixed in 5.11 (unaffected)
Vendor states this is fixed in 5.15.181 (unaffected)
Vendor states this is fixed in 6.1.135 (unaffected)
Vendor states this is fixed in 6.12.25 (unaffected)
Vendor states this is fixed in 6.14.4 (unaffected)
Vendor states this is fixed in 6.15 (unaffected)
Vendor states this is fixed in 6.6.88 (unaffected)

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

5.5MEDIUMCISA-ADP
Attack Vector
LOCAL
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-326

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