CVE-2020-21405Public exploit

Unrecoverable boot failure via unbounded environment writes

Published Jul 20, 2022 · Updated Aug 4, 2024

Denial of service in H96 Pro Plus firmware allows context-dependent attackers to render the device unbootable through a third-party Android app. The unprotected saveDeepColorAttr method in the SystemControl service appends its second string argument to /dev/block/env without bounding repeated calls, eventually corrupting boot environment data. Any installed third-party app can invoke the Binder transaction more than 10,000 times, after which the device cannot reboot even in safe mode.

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

What happened

Denial of service in H96 Pro Plus firmware allows context-dependent attackers to render the device unbootable through a third-party Android app. The unprotected saveDeepColorAttr method in the SystemControl service appends its second string argument to /dev/block/env without bounding repeated calls, eventually corrupting boot environment data. Any installed third-party app can invoke the Binder transaction more than 10,000 times, after which the device cannot reboot even in safe mode.

The record

CVE
CVE-2020-21405
Published
Jul 20, 2022
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-400, T1561.002
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

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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 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.

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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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
T1561.002Disk Structure Wipe

Public exploit references

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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