CVE-2025-39889 [High] | Security Vulnerability in Linux Kernel

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)

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2025-09-24	—	0.01%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2025-09-24

—

0.01%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
8.1	3.1	HIGH	`CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N` Click to expand Attack vector (AV:A) Attacker has to be nearby on the network—same office, same link, that vibe—not the whole wide internet. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:N) Service keeps running; no real outage angle.	2.8	5.2	416baaa9-dc9f-4396-8d5f-8c081fb06d67
5.5	3.1	MEDIUM	`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H` Click to expand Attack vector (AV:L) They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:L) A normal user session is enough; they don’t have to be admin. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:N) Doesn’t really leak secrets in a meaningful way. Integrity (I:N) Data isn’t meaningfully altered or forged. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	1.8	3.6	[email protected]
5.5	3.1	MEDIUM	`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H` Click to expand Attack vector (AV:L) They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:L) A normal user session is enough; they don’t have to be admin. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:N) Doesn’t really leak secrets in a meaningful way. Integrity (I:N) Data isn’t meaningfully altered or forged. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	1.8	3.6	134c704f-9b21-4f2e-91b3-4a467353bcc0

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

8.1

3.1

HIGH

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

Attack vector (AV:A): Attacker has to be nearby on the network—same office, same link, that vibe—not the whole wide internet.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N): No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H): Serious risk that confidential data gets exposed in a big way.
Integrity (I:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N): Service keeps running; no real outage angle.

2.8

5.2

416baaa9-dc9f-4396-8d5f-8c081fb06d67

5.5

3.1

MEDIUM

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

Attack vector (AV:L): They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L): A normal user session is enough; they don’t have to be admin.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N): Doesn’t really leak secrets in a meaningful way.
Integrity (I:N): Data isn’t meaningfully altered or forged.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

1.8

3.6

[email protected]

5.5

3.1

MEDIUM

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

Attack vector (AV:L): They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L): A normal user session is enough; they don’t have to be admin.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N): Doesn’t really leak secrets in a meaningful way.
Integrity (I:N): Data isn’t meaningfully altered or forged.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

1.8

3.6

134c704f-9b21-4f2e-91b3-4a467353bcc0

OS Trackers for CVE-2025-39889

vendor	priority	summary	link
`debian`	unimportant	CVE-2025-39889 unimportant priority: Debian including 1 source packages (linux), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5.	https://security-tracker.debian.org/tracker/CVE-2025-39889
`redhat`	medium	—	https://access.redhat.com/security/cve/CVE-2025-39889
`suse`	medium	CVE-2025-39889 severity moderate: SUSE including 459 source package names (2.1.3-6.80:kernel-default-base-6.4.0-35.1.21.12, 2.1.3-7.57:kernel-default-6.4.0-35.1, …), 907 product×package rows across 179 product lines (Container suse/sl-micro/6.0/base-os-container, Container suse/sl-micro/6.0/kvm-os-container, … (179 product lines)): Fixed 619, Known Affected 231, Known Not Affected 36, First Fixed 21.	https://www.suse.com/security/cve/CVE-2025-39889/
`ubuntu`	medium	CVE-2025-39889 medium priority: Ubuntu including 158 source packages (linux, linux-allwinner-5.19, …), 1414 status rows across 9 suites (bionic, focal, jammy, noble, plucky, questing, trusty, upstream, xenial): DNE 1017, ignored 159, released 158, not-affected 74, needs-triage 3, needed 2, pending 1.	https://ubuntu.com/security/CVE-2025-39889

Affected software / configurations for CVE-2025-39889

Vendor	Product	Version	Raw CPE
linux	linux_kernel	>= 5.11, < 5.15.181	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 5.16, < 6.1.135	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 6.2, < 6.6.88	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 6.7, < 6.12.25	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 6.13, < 6.14.4	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	6.15	cpe:2.3:o:linux:linux_kernel:6.15:rc1::::::
linux	linux_kernel	6.15	cpe:2.3:o:linux:linux_kernel:6.15:rc2::::::

References for CVE-2025-39889

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

URL

CVE-2025-39889 | Bluetooth: l2cap: Check encryption key size on incoming connection

Exploit prediction scoring system (EPSS) score for CVE-2025-39889

Common vulnerability scoring system (CVSS) metrics for CVE-2025-39889

Weakness enumeration for CVE-2025-39889

OS Trackers for CVE-2025-39889

Affected software / configurations for CVE-2025-39889

References for CVE-2025-39889