CVE-2021-20733
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 · uneditedImproper authorization in handler for custom URL scheme vulnerability in あすけんダイエット (asken diet) for Android versions from v.3.0.0 to v.4.2.x allows a remote attacker to lead a user to access an arbitrary website via the vulnerable App.
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 confidenceThe Android app 'あすけんダイエット' (asken diet) versions 3.0.0 through 4.2.x contains an improper authorization vulnerability in its custom URL scheme handler. Attackers can craft malicious links that cause the app to navigate users to arbitrary websites, potentially facilitating phishing or further malicious activities.
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>= 3.0.0, < 4.3.0CVSS 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
- Required
- Scope
- Changed
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/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 checksWork through these to decide whether this CVE applies to you.
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Confirm the app is installedOpen Android Settings > Apps and search for 'あすけん'or 'asken', or use ADB command: 'adb shell pm list packages | grep -i asken'Affected if the app 'あすけんダイエット' is present on the device
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Identify the package nameUse ADB command: 'adb shell pm list packages | grep -i asken' to find the package name (typically starts with 'jp.co.asken' or similar)Affected if a package containing 'asken' in the name exists
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Check the installed versionUse ADB: 'adb shell dumpsys package <package_name>' and look for versionName, or view the app info in Settings > Apps > [App Name] > App infoAffected if versionName shows a version from 3.0.0 through 4.2.x (less than 4.3.0)
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Verify version is within vulnerable rangeCompare the installed version number against the affected range: vulnerable if version >= 3.0.0 AND version < 4.3.0Affected if the installed version is 3.0.0, 3.1.0, 3.2.0, 4.0.x, 4.1.x, 4.2.x, or any version between 3.0.0 and 4.2.x inclusive
A user is affected if the app is installed and the version is 3.0.0 or higher but lower than 4.3.0, as this version range contains the vulnerable custom URL scheme handler.
Generated from the published advisory. Verify against your own configuration.
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.
From vendor data4.3.0
Implement proper validation and authorization for the custom URL scheme handler, including URL whitelist enforcement and user confirmation prompts before navigating to external websites.
- Consultation2.0 h
- Implementation8.0 h
- Testing4.0 h
- Review / QA3.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,768.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-20733 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-20733 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- 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
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