Linux Kernel up to 6.1.54/6.5.4 hci_unregister_dev reference count

CVSS Meta Temp Score
CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.
Current Exploit Price (≈)
Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.
CTI Interest Score
Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
4.6$0-$5k0.00

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.1.54/6.5.4. It has been rated as critical. This issue affects the function hci_unregister_dev. The manipulation leads to reference count. This vulnerability is uniquely identified as CVE-2023-53520. No exploit exists. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.1.54/6.5.4. It has been rated as critical. This issue affects the function hci_unregister_dev. The manipulation with an unknown input leads to a reference count vulnerability. Using CWE to declare the problem leads to CWE-911. The product uses a reference count to manage a resource, but it does not update or incorrectly updates the reference count. Impacted is availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: Fix hci_suspend_sync crash If hci_unregister_dev() frees the hci_dev object but hci_suspend_notifier may still be accessing it, it can cause the program to crash. Here's the call trace: <4>[102152.653246] Call Trace: <4>[102152.653254] hci_suspend_sync+0x109/0x301 [bluetooth] <4>[102152.653259] hci_suspend_dev+0x78/0xcd [bluetooth] <4>[102152.653263] hci_suspend_notifier+0x42/0x7a [bluetooth] <4>[102152.653268] notifier_call_chain+0x43/0x6b <4>[102152.653271] __blocking_notifier_call_chain+0x48/0x69 <4>[102152.653273] __pm_notifier_call_chain+0x22/0x39 <4>[102152.653276] pm_suspend+0x287/0x57c <4>[102152.653278] state_store+0xae/0xe5 <4>[102152.653281] kernfs_fop_write+0x109/0x173 <4>[102152.653284] __vfs_write+0x16f/0x1a2 <4>[102152.653287] ? selinux_file_permission+0xca/0x16f <4>[102152.653289] ? security_file_permission+0x36/0x109 <4>[102152.653291] vfs_write+0x114/0x21d <4>[102152.653293] __x64_sys_write+0x7b/0xdb <4>[102152.653296] do_syscall_64+0x59/0x194 <4>[102152.653299] entry_SYSCALL_64_after_hwframe+0x5c/0xc1 This patch holds the reference count of the hci_dev object while processing it in hci_suspend_notifier to avoid potential crash caused by the race condition.

It is possible to read the advisory at git.kernel.org. The identification of this vulnerability is CVE-2023-53520 since 10/01/2025. The exploitation is known to be difficult. Technical details of the vulnerability are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 307006 (Ubuntu 20.04 LTS / 22.04 LTS : Linux kernel vulnerabilities (USN-8180-1)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.1.55 or 6.5.5 eliminates this vulnerability. Applying the patch 06e2b5ad72b60f90bfe565c201346532e271f484/f9c8ce5d665653e3cf71a76349d41d7a7f7947e6/573ebae162111063eedc6c838a659ba628f66a0f is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (307006), EUVD (EUVD-2025-32747) and CERT Bund (WID-SEC-2025-2187). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Affected

  • Amazon Linux 2
  • Red Hat Enterprise Linux
  • SUSE Linux
  • Oracle Linux
  • Open Source Linux Kernel
  • Dell Secure Connect Gateway

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 4.8
VulDB Meta Temp Score: 4.6

VulDB Base Score: 4.8
VulDB Temp Score: 4.6
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 4.7
NVD Vector: 🔒

CVSSv2info

AVACAuCIA
💳💳💳💳💳💳
💳💳💳💳💳💳
💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
UnlockUnlockUnlockUnlockUnlockUnlock
UnlockUnlockUnlockUnlockUnlockUnlock
UnlockUnlockUnlockUnlockUnlockUnlock

VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Reference count
CWE: CWE-911 / CWE-664
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

0-DayUnlockUnlockUnlockUnlock
TodayUnlockUnlockUnlockUnlock

Nessus ID: 307006
Nessus Name: Ubuntu 20.04 LTS / 22.04 LTS : Linux kernel vulnerabilities (USN-8180-1)

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.1.55/6.5.5
Patch: 06e2b5ad72b60f90bfe565c201346532e271f484/f9c8ce5d665653e3cf71a76349d41d7a7f7947e6/573ebae162111063eedc6c838a659ba628f66a0f

Timelineinfo

10/01/2025 Advisory disclosed
10/01/2025 +0 days CVE reserved
10/01/2025 +0 days VulDB entry created
04/19/2026 +200 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2023-53520 (🔒)
GCVE (CVE): GCVE-0-2023-53520
GCVE (VulDB): GCVE-100-326627
EUVD: 🔒
CERT Bund: WID-SEC-2025-2187 - Linux Kernel: Mehrere Schwachstellen erm&ouml;glichen Denial of Service

Entryinfo

Created: 10/01/2025 15:23
Updated: 04/19/2026 21:36
Changes: 10/01/2025 15:23 (58), 11/29/2025 04:32 (7), 01/27/2026 03:39 (10), 01/27/2026 16:38 (1), 04/19/2026 21:36 (2)
Complete: 🔍
Cache ID: 216::103

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Discussion

No comments yet. Languages: en.

Please log in to comment.

◂ PreviousOverviewNext ▸

Interested in the pricing of exploits?

See the underground prices here!