CVE-2020-21406Public exploit

HDMI output denial via unprotected display service

Published Jul 20, 2022 · Updated Aug 4, 2024

Denial of service in RK Smart TV Box MAX and V88 SmartTV box allows local users to disable HDMI output via a system service call. The unprotected display_device_management Binder service accepts transaction 7 with integer 0 and drops the HDMI signal. Any unprivileged malicious app installed on either Android-based device can invoke the custom API, disabling streaming and other HDMI-delivered functions.

CVSS severity7.5
High
EPSS probability0.92%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Denial of service in RK Smart TV Box MAX and V88 SmartTV box allows local users to disable HDMI output via a system service call. The unprotected display_device_management Binder service accepts transaction 7 with integer 0 and drops the HDMI signal. Any unprivileged malicious app installed on either Android-based device can invoke the custom API, disabling streaming and other HDMI-delivered functions.

The record

CVE
CVE-2020-21406
Published
Jul 20, 2022
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
T1642
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 20, 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

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

T1642Endpoint Denial of Service

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo