CVE-2023-20821

Local privilege escalation via unchecked nvram write

Published Sep 4, 2023 · Updated Oct 10, 2024

Out-of-bounds write in MediaTek nvram on affected chipsets allows local users with System privileges to escalate privileges. The nvram component processes input without checking its bounds, permitting a write beyond the intended buffer. Exploitation is local, requires existing System execution privileges, and needs no user interaction; successful exploitation raises privileges on the device.

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 nvram on affected chipsets allows local users with System privileges to escalate privileges. The nvram component processes input without checking its bounds, permitting a write beyond the intended buffer. Exploitation is local, requires existing System execution privileges, and needs no user interaction; successful exploitation raises privileges on the device.

The record

CVE
CVE-2023-20821
Published
Sep 4, 2023
Updated
Oct 10, 2024
Vendor
MediaTek
Product
MT8173
Classifications
CWE-787, CWE-20, T1068
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Sep 4, 2023CVE publishedPublication date reported by the CVE source.
  2. Oct 10, 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=0 <=*

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

MediaTek · MT8173version=0 <=*
MediaTek · MT8175version=0 <=*
MediaTek · MT8768version=0 <=*
MediaTek · MT6889version=0 <=*
MediaTek · MT6880version=0 <=*
MediaTek · MT6875version=0 <=*
MediaTek · MT6835version=0 <=*
MediaTek · MT6891version=0 <=*
MediaTek · MT6980version=0 <=*
MediaTek · MT6890version=0 <=*
MediaTek · MT8167Sversion=0 <=*
MediaTek · MT6855version=0 <=*
MediaTek · MT8766version=0 <=*
MediaTek · MT6990version=0 <=*
MediaTek · MT2735version=0 <=*
MediaTek · MT6893version=0 <=*
MediaTek · MT6885version=0 <=*
MediaTek · MT8666version=0 <=*
MediaTek · MT8385version=0 <=*
MediaTek · MT8791Tversion=0 <=*
MediaTek · MT6879version=0 <=*
MediaTek · MT6873version=0 <=*
MediaTek · MT8791version=0 <=*
MediaTek · MT8195version=0 <=*
MediaTek · MT6877version=0 <=*
MediaTek · MT6886version=0 <=*
MediaTek · MT8786version=0 <=*
MediaTek · MT8395version=0 <=*
Google · Androidversion=12.0; version=13.0
MediaTek · MT8675version=0 <=*
MediaTek · MT6853version=0 <=*
MediaTek · MT8781version=0 <=*
MediaTek · MT8321version=0 <=*
MediaTek · MT8789version=0 <=*
MediaTek · MT8673version=0 <=*
MediaTek · MT8185version=0 <=*
MediaTek · MT6883version=0 <=*
MediaTek · MT6985version=0 <=*
MediaTek · MT8167version=0 <=*
MediaTek · MT8365version=0 <=*
MediaTek · MT8788version=0 <=*
MediaTek · MT8188version=0 <=*
MediaTek · MT6833version=0 <=*
MediaTek · MT8797version=0 <=*
MediaTek · MT6983version=0 <=*
MediaTek · MT8362Aversion=0 <=*
MediaTek · MT8168version=0 <=*
MediaTek · MT2713version=0 <=*
MediaTek · MT8765version=0 <=*
MediaTek · MT6895version=0 <=*

Published CVSS scores

6.7NIST NVDCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
6.7CISA-ADPCVSS: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.

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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
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write
CWE-20Improper Input Validation
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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