CVE-2021-32399Public exploit

Local privilege escalation via HCI removal race

Published May 10, 2021 · Updated Aug 3, 2024

A race condition in the Linux kernel Bluetooth subsystem through 5.12.2 allows local users to crash the kernel or escalate privileges. hci_req_sync checks HCI_UP before taking hdev->req_lock, allowing hci_dev_do_close to clear the flag and free the HCI device before queued command work dereferences it. Triggering requires repeated controller closure concurrent with HCI command issuance; real controllers need no added privilege, while activating a fake controller requires CAP_NET_ADMIN.

CVSS severity7.0
High
EPSS probability0.69%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A race condition in the Linux kernel Bluetooth subsystem through 5.12.2 allows local users to crash the kernel or escalate privileges. hci_req_sync checks HCI_UP before taking hdev->req_lock, allowing hci_dev_do_close to clear the flag and free the HCI device before queued command work dereferences it. Triggering requires repeated controller closure concurrent with HCI command issuance; real controllers need no added privilege, while activating a fake controller requires CAP_NET_ADMIN.

The record

CVE
CVE-2021-32399
Published
May 10, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-362, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 10, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.0Oracle LinuxCVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
7.0NIST NVDCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
4.4NIST NVDAV:L/AC:M/Au:N/C:P/I:P/A:P

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
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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