CVE-2021-3573Public exploit

Privilege escalation via Bluetooth HCI race

Published Aug 13, 2021 · Updated Aug 3, 2024

Use-after-free in the Linux kernel Bluetooth HCI subsystem before 5.13-rc5 allows local users to crash the system or escalate privileges. The hci_sock_bound_ioctl path retains an hci_dev reference while copy_from_user can stall, allowing hci_unregister_dev to free the device before blacklist or connection handlers resume using it. Local access with elevated privileges is required, and winning the race can corrupt the kernel heap, panic the system, or elevate execution in the kernel.

CVSS severity6.4
Medium
EPSS probability0.37%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in the Linux kernel Bluetooth HCI subsystem before 5.13-rc5 allows local users to crash the system or escalate privileges. The hci_sock_bound_ioctl path retains an hci_dev reference while copy_from_user can stall, allowing hci_unregister_dev to free the device before blacklist or connection handlers resume using it. Local access with elevated privileges is required, and winning the race can corrupt the kernel heap, panic the system, or elevate execution in the kernel.

The record

CVE
CVE-2021-3573
Published
Aug 13, 2021
Updated
Aug 3, 2024
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-362, CAPEC-26, T1068
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Aug 13, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record 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=kernel 5.13-rc5

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

The Linux Kernel Organization · Linux Kernelversion=kernel 5.13-rc5

Published CVSS scores

6.4NIST NVDCVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesadmin
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
CAPEC-26Leveraging Race Conditions
T1068Exploitation for Privilege Escalation

Public exploit references

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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