CVE-2021-43400Network attack vector

Memory corruption via uncleared pending GATT operation

Published Nov 4, 2021 · Updated Nov 4, 2025

Use-after-free in BlueZ 5.40 through 5.61 allows remote attackers to corrupt memory by disconnecting during a GATT WriteValue call. The GATT database leaves an asynchronous D-Bus operation pending without disconnect cleanup, allowing its reply path to use device state released with the client connection. Reachability requires a Bluetooth client connection to the GATT server and precise disconnection during processing; published sources do not establish whether the corruption produces a crash, data access, or code execution.

CVSS severity9.1
Critical
EPSS probability1.66%
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 BlueZ 5.40 through 5.61 allows remote attackers to corrupt memory by disconnecting during a GATT WriteValue call. The GATT database leaves an asynchronous D-Bus operation pending without disconnect cleanup, allowing its reply path to use device state released with the client connection. Reachability requires a Bluetooth client connection to the GATT server and precise disconnection during processing; published sources do not establish whether the corruption produces a crash, data access, or code execution.

The record

CVE
CVE-2021-43400
Published
Nov 4, 2021
Updated
Nov 4, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-416
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 4, 2021CVE publishedPublication date reported by the CVE source.
  2. Nov 4, 2025Record 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 vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

9.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
6.4NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:N

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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free

Public exploit references

No public exploit references are available in this record.

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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