CVE-2025-39889

Security policy bypass via unchecked encryption key

Published Sep 24, 2025 · Updated Sep 24, 2025

Inadequate encryption-strength validation in affected Linux kernel versions allows physically proximate attackers to establish an L2CAP connection. The l2cap_connect function checks ACL link mode but fails to call l2cap_check_enc_key_size before accepting a non-SDP connection. The peer must be within Bluetooth range and negotiate Security Mode 4 Level 4 with a 1-to-15-byte key; the observed consequence is acceptance of a channel that should receive a security-block refusal.

CVSS severity5.5
Medium
EPSS probability0.10%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Inadequate encryption-strength validation in affected Linux kernel versions allows physically proximate attackers to establish an L2CAP connection. The l2cap_connect function checks ACL link mode but fails to call l2cap_check_enc_key_size before accepting a non-SDP connection. The peer must be within Bluetooth range and negotiate Security Mode 4 Level 4 with a 1-to-15-byte key; the observed consequence is acceptance of a channel that should receive a security-block refusal.

The record

CVE
CVE-2025-39889
Published
Sep 24, 2025
Updated
Sep 24, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-326
Attack vector
adjacent
Privileges
Unavailable

Timeline

How it unfolded

  1. Sep 24, 2025CVE publishedPublication date reported by the CVE source.
  2. Sep 24, 2025Record 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=288c06973daae4637f25a0d1bdaf65fdbf8455f9 <24b2cdfc16e9bd6ab3d03b8e01c590755bd3141f
  2. Affected versionversion=288c06973daae4637f25a0d1bdaf65fdbf8455f9 <522e9ed157e3c21b4dd623c79967f72c21e45b78
  3. Affected versionversion=288c06973daae4637f25a0d1bdaf65fdbf8455f9 <9e3114958d87ea88383cbbf38c89e04b8ea1bce5
  4. Affected versionversion=288c06973daae4637f25a0d1bdaf65fdbf8455f9 <c6d527bbd3d3896375079f5dbc8b7f96734a3ba5
  5. Affected versionversion=288c06973daae4637f25a0d1bdaf65fdbf8455f9 <d49798ecd26e0ee7995a7fc1e90ca5cd9b4402d6
  6. Affected versionversion=288c06973daae4637f25a0d1bdaf65fdbf8455f9 <d4ca2fd218caafbf50e3343ba1260c6a23b5676a
  7. Affected versionversion=5.11

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesUnavailable in this record.

What is affected?

The Linux Kernel Organization · Linuxversion=288c06973daae4637f25a0d1bdaf65fdbf8455f9 <24b2cdfc16e9bd6ab3d03b8e01c590755bd3141f; version=288c06973daae4637f25a0d1bdaf65fdbf8455f9 <522e9ed157e3c21b4dd623c79967f72c21e45b78; version=288c06973daae4637f25a0d1bdaf65fdbf8455f9 <9e3114958d87ea88383cbbf38c89e04b8ea1bce5; version=288c06973daae4637f25a0d1bdaf65fdbf8455f9 <c6d527bbd3d3896375079f5dbc8b7f96734a3ba5; version=288c06973daae4637f25a0d1bdaf65fdbf8455f9 <d49798ecd26e0ee7995a7fc1e90ca5cd9b4402d6; version=288c06973daae4637f25a0d1bdaf65fdbf8455f9 <d4ca2fd218caafbf50e3343ba1260c6a23b5676a; version=5.11

Published CVSS scores

5.5CISA ADP VulnrichmentCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

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.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-326Inadequate Encryption Strength

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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