CVE-2021-0897

Local privilege escalation via TOCTOU buffer race

Published Dec 17, 2021 · Updated Aug 3, 2024

Out-of-bounds write in MediaTek apusys on Android 10.0 through 12.0 allows local users with System privileges to escalate privileges. A time-of-check/time-of-use race lets an attacker change shared buffer state after validation, so apusys writes beyond the validated bounds. Exploitation requires System execution privileges on an affected MediaTek chipset, but no user interaction; the resulting privilege level is not publicly specified.

CVSS severity6.7
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

Out-of-bounds write in MediaTek apusys on Android 10.0 through 12.0 allows local users with System privileges to escalate privileges. A time-of-check/time-of-use race lets an attacker change shared buffer state after validation, so apusys writes beyond the validated bounds. Exploitation requires System execution privileges on an affected MediaTek chipset, but no user interaction; the resulting privilege level is not publicly specified.

The record

CVE
CVE-2021-0897
Published
Dec 17, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-367, CWE-787, T1068
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Dec 17, 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 privilegesadmin

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
6.7NIST NVDCVSS:3.1/AV:L/AC:L/PR:H/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-367Time-of-check Time-of-use (TOCTOU) Race Condition
CWE-787Out-of-bounds Write
T1068Exploitation for Privilege Escalation

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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