CVE-2021-33034Public exploit

Local code execution via freed Bluetooth channel

Published May 14, 2021 · Updated Aug 3, 2024

Use-after-free in the Linux kernel before 5.12.4 allows local users to crash the system or execute arbitrary code through Bluetooth HCI. hci_disconn_loglink_complete_evt destroys hchan without verifying that it is the AMP channel, and hci_send_acl later dereferences the freed object. The path requires a low-privileged local user able to drive affected Bluetooth HCI and L2CAP activity; exploitation corrupts kernel memory or stops the host.

CVSS severity7.8
High
EPSS probability0.82%
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 before 5.12.4 allows local users to crash the system or execute arbitrary code through Bluetooth HCI. hci_disconn_loglink_complete_evt destroys hchan without verifying that it is the AMP channel, and hci_send_acl later dereferences the freed object. The path requires a low-privileged local user able to drive affected Bluetooth HCI and L2CAP activity; exploitation corrupts kernel memory or stops the host.

The record

CVE
CVE-2021-33034
Published
May 14, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-416, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 14, 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

4.6NIST NVDAV:L/AC:L/Au:N/C:P/I:P/A:P
7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-416Use After Free
T1499.004Application or System Exploitation

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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