CVE-2021-0657

Local privilege escalation via apusys stack overflow

Published Nov 18, 2021 · Updated Aug 3, 2024

Stack-based buffer overflow in MediaTek apusys on Android 10.0 allows local users to elevate privileges through an out-of-bounds write. The apusys component writes beyond a stack buffer, but MediaTek has not published the affected function, input path, or malformed data structure. Exploitation requires System execution privileges and no user interaction, and the reported consequence is additional local privilege rather than remote access.

CVSS severity6.7
Medium
EPSS probability0.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stack-based buffer overflow in MediaTek apusys on Android 10.0 allows local users to elevate privileges through an out-of-bounds write. The apusys component writes beyond a stack buffer, but MediaTek has not published the affected function, input path, or malformed data structure. Exploitation requires System execution privileges and no user interaction, and the reported consequence is additional local privilege rather than remote access.

The record

CVE
CVE-2021-0657
Published
Nov 18, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-787, CWE-121, T1404
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Nov 18, 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 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-787Out-of-bounds Write
CWE-121Stack-based Buffer Overflow
T1404Exploitation 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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