dbcve.org
TizenOperating system · Linux

CVE-2021-25434

CRITICAL · 9.8 CVSS v3.1 Published 2021-07-08
Fix available
A fix is available. Upgrade to 5.5 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Improper input validation vulnerability in Tizen bootloader prior to Firmware update JUL-2021 Release allows arbitrary code execution using param partition in wireless firmware download mode.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A critical input validation flaw in the Tizen bootloader allows attackers to execute arbitrary code by manipulating the param partition during wireless firmware download mode. The vulnerability stems from insufficient validation of firmware update parameters, enabling an attacker to inject malicious code that executes with bootloader-level privileges before the main OS loads.

MitigationApply the JUL-2021 Firmware update (or later) to all affected Tizen devices to patch the bootloader input validation vulnerability. If immediate patching is not possible, disable wireless firmware download mode as a compensating control.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
TizenOperating system
Affected:< 5.5

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify if the device runs Tizen OS
    Check the OS identification file or boot messages for 'Tizen' or check /etc/os-release (if accessible) for Tizen-specific entries
    Affected if The device is not running Tizen OS (this CVE only affects Tizen)
  2. Determine the installed Tizen version
    Check /etc/os-release or the Tizen version file (commonly /etc/tizen-release or via 'getprop ro.build.version.tizen' command if available)
    Affected if The Tizen version is below 5.5 (versions < 5.5 are affected)
  3. Verify wireless firmware download mode status
    Check the bootloader configuration or settings for 'Firmware Download Mode', 'OtaUpdate', or wireless firmware update functionality - this is typically in the bootloader parameters or device settings menus
    Affected if Wireless firmware download mode is enabled (this is the attack vector for this CVE)
  4. Inspect the param partition for modification indicators
    Examine the bootloader param partition (typically /param or via fastboot/oem commands) for unexpected or suspicious parameter entries related to firmware updates
    Affected if Unexpected parameters exist in the firmware update configuration or param partition
  5. Review bootloader configuration files
    Look for bootloader configuration files (such as /boot or uboot config) that control firmware update behavior and validate that parameter checking is enforced
    Affected if Bootloader lacks proper input validation controls for firmware parameters

A Tizen device is affected if it runs version below 5.5 AND has wireless firmware download mode enabled, as this mode is required as the attack vector for the vulnerability.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 5.5 or later
Fixed in 5.5
Interim mitigation

Apply the JUL-2021 Firmware update (or later) to all affected Tizen devices to patch the bootloader input validation vulnerability. If immediate patching is not possible, disable wireless firmware download mode as a compensating control.

Recommended fix High confidence

Tizen 5.5 or JUL-2021 firmware release

  1. Update the device firmware to the JUL-2021 Release or later, which includes the security patch for this vulnerability
  2. Ensure the Tizen firmware is upgraded to version 5.5 or higher to receive the proper input validation fix in the bootloader
  3. After updating, verify the bootloader version reflects the patched release
Caveat Firmware updates on embedded devices carry inherent risks; ensure stable power during update and follow manufacturer update procedures

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Tizen Scoped from the published advisory
  • Consultation8.0 h
  • Implementation16.0 h
  • Testing24.0 h
  • Review / QA12.0 h
60.0 hours of engineering $10,240
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $16,384.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-25434 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data