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CVE-2025-39889

18
FAUCET Score

CVE-2025-39889 addresses a vulnerability in the Linux kernel's Bluetooth L2CAP component that failed to enforce proper encryption key size validation for incoming connections. This flaw allowed connections with insufficient key sizes (1-15 bytes) to succeed, bypassing the required 16-byte minimum for Security Mode 4 Level 4. Rated Medium severity (CVSS 5.5), the vulnerability has a high availability impact (A:H) and requires local access with low privileges for exploitation, stemming from inadequate encryption strength (CWE-326). There is currently no evidence of active exploitation, public exploit code, or inclusion in CISA's Known Exploited Vulnerabilities catalog. Community discussion and media coverage are minimal, indicating limited current threat activity.

Impacted Technologies

VendorProductVersion(s)CPE
>= 5.11, < 5.15.181CPE matchmatch criteria
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
>= 5.16, < 6.1.135CPE matchmatch criteria
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
>= 6.2, < 6.6.88CPE matchmatch criteria
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
>= 6.7, < 6.12.25CPE matchmatch criteria
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
>= 6.13, < 6.14.4CPE matchmatch criteria
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

8.1HIGH

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Attack Vector
ADJACENT_NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
NONE
Exploitability Score
2.8
Impact Score
5.2
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.09%
Probability of exploitation in next 30 days
EPSS Percentile
0.6%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0009 is in the 4th percentile among its peer group of 15,940 CVEs.

Social Chatter

No social media mentions found for this CVE.

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.0 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (11)

ubuntupatch availablevia ubuntu_usn
Product: linux-xilinx (noble)Fixed in: 6.8.0-1023.24
ubuntupatch availablevia ubuntu_usn
Product: linux-ibm-6.8 (jammy)Fixed in: 6.8.0-1044.44~22.04.1
ubuntupatch availablevia ubuntu_usn
Product: linux-ibm (noble)Fixed in: 6.8.0-1044.44
ubuntupatch availablevia ubuntu_usn
Product: linux-azure-fips (noble)Fixed in: 6.8.0-1046.52+fips1
ubuntupatch availablevia ubuntu_usn
Product: linux-azure (noble)Fixed in: 6.8.0-1046.52
ubuntupatch availablevia ubuntu_usn
Product: linux-azure-6.8 (jammy)Fixed in: 6.8.0-1051.57~22.04.1
redhatvendor investigatingvia redhat_api
Product: Red Hat Enterprise Linux 9Fixed in: kernel
redhatvendor investigatingvia redhat_api
Product: Red Hat Enterprise Linux 9Fixed in: kernel-rt
redhatvendor investigatingvia redhat_api
Product: Red Hat Enterprise Linux 10Fixed in: kernel
redhatvendor investigatingvia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: kernel
redhatvendor investigatingvia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: kernel-rt

Vendor Advisories (6)

ubuntuUSN-8126-1

Linux kernel (Azure) vulnerabilities

Mar 25, 2026
ubuntuUSN-8074-2

Linux kernel (Azure FIPS) vulnerabilities

Mar 4, 2026
ubuntuUSN-8074-1

Linux kernel (Azure) vulnerabilities

Mar 4, 2026
ubuntuUSN-8052-2

Linux kernel (Xilinx) vulnerabilities

Feb 24, 2026
ubuntuUSN-8028-8

Linux kernel (IBM) vulnerabilities

Feb 24, 2026
redhatCVE-2025-39889Moderate

kernel: Bluetooth: l2cap: Check encryption key size on incoming connection

Sep 24, 2025

References

git.kernel.org / stable/c/24b2cdfc16e9bd6ab3d03b8e01c590755bd3141f
Patch
git.kernel.org / stable/c/522e9ed157e3c21b4dd623c79967f72c21e45b78
Patch
git.kernel.org / stable/c/9e3114958d87ea88383cbbf38c89e04b8ea1bce5
Patch
git.kernel.org / stable/c/c6d527bbd3d3896375079f5dbc8b7f96734a3ba5
Patch
git.kernel.org / stable/c/d49798ecd26e0ee7995a7fc1e90ca5cd9b4402d6
Patch
git.kernel.org / stable/c/d4ca2fd218caafbf50e3343ba1260c6a23b5676a
Patch
git.kernel.org / stable/c/ed503d340a501e414114ddc614a3aae4f6e9eae2