CVE-2021-39681

Local privilege escalation via delete_protocol use after free

Published Jan 14, 2022 · Updated Aug 4, 2024

Elevation of privilege in Android kernel allows local users to execute arbitrary code through a use-after-free in delete_protocol. The delete_protocol function in main.c uses memory after it has been freed, enabling arbitrary kernel code execution and privilege escalation. Exploitation requires a locally running application on an affected Android device and no user interaction; the resulting impact is bounded to elevated privileges on the device.

CVSS severity7.8
High
EPSS probability0.11%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Elevation of privilege in Android kernel allows local users to execute arbitrary code through a use-after-free in delete_protocol. The delete_protocol function in main.c uses memory after it has been freed, enabling arbitrary kernel code execution and privilege escalation. Exploitation requires a locally running application on an affected Android device and no user interaction; the resulting impact is bounded to elevated privileges on the device.

The record

CVE
CVE-2021-39681
Published
Jan 14, 2022
Updated
Aug 4, 2024
Vendor
Google Cloud
Product
Android
Classifications
CWE-416, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 14, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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?

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  1. Affected versionversion=Android kernel

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Google Cloud · Androidversion=Android kernel

Published CVSS scores

7.8NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
4.6NVDAV:L/AC:L/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 exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
T1068Exploitation for Privilege Escalation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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