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AndroidOperating system · Google

CVE-2021-25459

MEDIUM · 5.5 CVSS v3.1 Published 2021-09-09
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
57/100
Remediation priority · Elevated
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
An improper access control vulnerability in sspInit() in BlockchainTZService prior to SMR Sep-2021 Release 1 allows attackers to start BlockchainTZService.

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 · moderate confidence

An improper access control vulnerability in the sspInit() function of BlockchainTZService allows unauthenticated attackers to start the BlockchainTZService. The function lacks proper authorization checks before initializing the service, enabling any caller to invoke service startup despite requiring elevated privileges.

MitigationApply the SMR Sep-2021 Release 1 patch which implements proper access control validation in sspInit() to ensure only authorized callers can start BlockchainTZService. Verify that service initialization now requires appropriate authentication/authorization.

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
AndroidOperating system
Affected:= 10.0= 11.0

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
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

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

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. Check your Android version
    Go to Settings > About Phone > Android version and verify if it reads 10.0 or 11.0
    Affected if The Android version is exactly 10.0 or 11.0, as these are the affected versions listed in the CVE
  2. Confirm BlockchainTZService presence
    Check if the BlockchainTZService is installed on the device by reviewing system services or using ADB command: 'adb shell dumpsys -l' and search for BlockchainTZService in the output
    Affected if The BlockchainTZService is present on the device, as the vulnerability exists within this specific service
  3. Verify service authorization configuration
    Examine the service configuration for BlockchainTZService by using ADB: 'adb shell dumpsys package <service_name>' or inspect the service's manifest/permissions to determine if authorization checks are enforced on sspInit()
    Affected if The sspInit() function lacks proper authorization checks, allowing any caller to invoke service startup without elevated privilege validation
  4. Test service initialization accessibility
    Attempt to query or trigger the BlockchainTZService startup through ADB: 'adb shell am startservice -n <package>/.BlockchainTZService' to see if it can be invoked without authentication credentials
    Affected if The service can be started by any caller without requiring authentication or authorization, indicating the vulnerability is present

You are affected if your device runs Android 10.0 or 11.0, contains the BlockchainTZService, and the sspInit() function allows unauthenticated service initialization without proper access control validation.

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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the SMR Sep-2021 Release 1 patch which implements proper access control validation in sspInit() to ensure only authorized callers can start BlockchainTZService. Verify that service initialization now requires appropriate authentication/authorization.

Recommended fix High confidence

SMR Sep-2021 Release 1 (or later)

  1. Verify the device model is a Samsung Galaxy device running Android 10.0 or 11.0
  2. Navigate to Settings > Software Update on the device
  3. Check for and install the latest Samsung security update (SMR Sep-2021 Release 1 or later)
  4. After updating, verify the patch has been applied by checking Settings > About Phone > Software Information > Security patch level
  5. Ensure the Security patch level shows a date on or after September 2021
Caveat Samsung monthly security updates typically do not introduce breaking changes; however, always backup important data before applying system updates

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

Fix this in Android Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,930
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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-2021-25459 in production — separate from our analysis above.

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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