CVE-2021-39735

Local privilege escalation via coherent-memory allocation race

Published Mar 16, 2022 · Updated Aug 4, 2024

Memory corruption in the Android kernel allows local users with System execution privileges to elevate privileges without user interaction. The gasket_alloc_coherent_memory function in gasket_page_table.c allocates coherent page-table memory without sufficient synchronization, allowing concurrent execution to corrupt memory. Exploitation requires local access and existing System execution privileges; successful exploitation raises privileges without user action.

CVSS severity6.4
Medium
EPSS probability0.09%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory corruption in the Android kernel allows local users with System execution privileges to elevate privileges without user interaction. The gasket_alloc_coherent_memory function in gasket_page_table.c allocates coherent page-table memory without sufficient synchronization, allowing concurrent execution to corrupt memory. Exploitation requires local access and existing System execution privileges; successful exploitation raises privileges without user action.

The record

CVE
CVE-2021-39735
Published
Mar 16, 2022
Updated
Aug 4, 2024
Vendor
Google Cloud
Product
Android
Classifications
CWE-362, T1068
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Mar 16, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=Android kernel

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

Google Cloud · Androidversion=Android kernel

Published CVSS scores

6.4NVDCVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
4.4NVDAV: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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

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