CVE-2021-25435

Code execution via unchecked recovery-partition input

Published Jul 8, 2021 · Updated Aug 3, 2024

Improper input validation in Samsung Tizen allows attackers to execute arbitrary code through wireless firmware download mode. The bootloader fails to validate recovery-partition input before processing it during a wireless firmware download. Exploitation requires local access and user interaction to use that mode; successful exploitation executes code in the bootloader context.

CVSS severity9.8
Critical
EPSS probability1.68%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in Samsung Tizen allows attackers to execute arbitrary code through wireless firmware download mode. The bootloader fails to validate recovery-partition input before processing it during a wireless firmware download. Exploitation requires local access and user interaction to use that mode; successful exploitation executes code in the bootloader context.

The record

CVE
CVE-2021-25435
Published
Jul 8, 2021
Updated
Aug 3, 2024
Vendor
Samsung Electronics
Product
Tizen
Classifications
CWE-20, T1203
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 8, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=Tizen 5.5 <Firmware update JUL-2021 Release

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Samsung Electronics · Tizenversion=Tizen 5.5 <Firmware update JUL-2021 Release

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:P

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 exploitUnconfirmed

Weakness, pattern, technique

CWE-20Improper Input Validation
T1203Exploitation for Client Execution

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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