Vulnerability in Linux kernel (CVE-2025-39889)
Summary
Vulnerability in Linux kernel (CVE-2025-39889). Confidential information can be exposed externally.
Original description
The description as published by the source.
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: NIST National Vulnerability Database NVD
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2025-39889 has been found in Linux kernel.
Confidential information can be exposed externally. CVSS score: 8.1/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Linux kernel CVE-2025-39889" on the vendor's site.
CVE-2025-39889 (Linux kernel) — CWE-326 / CVSS v3 8.1
Attack vector: adjacent-network / unauthenticated / no user interaction
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-326) exists in Linux kernel.
Check the vendor advisory for the affected versions of Linux kernel.
Severity: High (CVSS 8.1/10). Confidential information can be exposed externally.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
Audit SBOM/dependencies for affected components.資産台帳・SBOM・依存マニフェストで Linux kernel を使っているサービスとバージョンを洗い出す。
-
2Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Fix status by distribution
Fixed packages published by each distribution for this CVE
- BellSoft Alpaquita BELL-CVE-2025-39889 linux-lts Fixed in: 6.1.140-r0
- Debian DEBIAN-CVE-2025-39889 linux Fixed in: 6.1.135-1
- Ubuntu UBUNTU-CVE-2025-39889 linux-hwe-edge
References
- patch git.kernel.org
- patch git.kernel.org
- patch git.kernel.org
- patch git.kernel.org
- patch git.kernel.org
- patch git.kernel.org
- web git.kernel.org