CVE-2021-39806

Local privilege escalation via duplicate backend cleanup

Published Jun 15, 2022 · Updated Aug 4, 2024

Double free in the Android 12L Framework allows local users to escalate privileges during servicemanager startup without user interaction. The property backend closef routine frees backend state after an initialization error, and selabel_close then invokes the same cleanup routine again. Exploitation requires a local user to trigger that initialization failure during servicemanager startup, enabling memory corruption and privilege escalation.

CVSS severity7.8
High
EPSS probability0.10%
Next 30 days · Sep 17, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Double free in the Android 12L Framework allows local users to escalate privileges during servicemanager startup without user interaction. The property backend closef routine frees backend state after an initialization error, and selabel_close then invokes the same cleanup routine again. Exploitation requires a local user to trigger that initialization failure during servicemanager startup, enabling memory corruption and privilege escalation.

The record

CVE
CVE-2021-39806
Published
Jun 15, 2022
Updated
Aug 4, 2024
Vendor
Google Cloud
Product
Android
Classifications
CWE-415, T1404
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 15, 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-12L

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Google Cloud · Androidversion=Android-12L

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.

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No observations available

Sep 11, 2026Sep 17, 2026
Latest reporting daySep 17, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-415Double Free
T1404Exploitation 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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