CVE-2021-44164
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 · uneditedChain Sea ai chatbot system’s file upload function has insufficient filtering for special characters in URLs, which allows a remote attacker to by-pass file type validation, upload malicious script and execute arbitrary code without authentication, in order to take control of the system or terminate service.
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 confidenceThe Chain Sea ai chatbot system contains a file upload vulnerability where insufficient filtering of special characters in URLs allows attackers to bypass file type validation. This enables unauthenticated remote attackers to upload malicious scripts (likely web shells) and execute arbitrary code, potentially gaining full system control or causing service disruption.
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 dataall versionsCVSS 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 checksWork through these to decide whether this CVE applies to you.
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Identify if the Chinasea Qb Smart Service Robot is deployedInventory your network or check running services for the Chain Sea ai chatbot system. Look for the Qb Smart Service Robot product or service.Affected if The Chinasea Qb Smart Service Robot or Chain Sea ai chatbot is running in your environment.
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Locate the file upload functionalityReview the web application or service configuration for endpoints that handle file uploads. Common paths include /upload, /file/upload, or similar endpoints in the chatbot admin interface.Affected if File upload functionality is present and accessible.
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Verify file type validation mechanismInspect server-side code or configuration files that handle uploaded files. Check if validation relies only on file extension or MIME type without checking magic bytes/file signatures.Affected if Validation uses only file extension or MIME type without magic byte verification.
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Check special character filteringReview input validation logic for URL and filename parameters. Look for whether special characters in filenames are filtered or sanitized before processing.Affected if No server-side sanitization of special characters in filenames or URLs is implemented.
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Inspect upload directory configurationCheck where uploaded files are stored relative to the webroot. Determine if uploaded files remain within the web-accessible directory tree.Affected if Uploaded files are stored inside the webroot or web-accessible directory.
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Verify script execution settingsExamine web server or application configuration for the upload directory. Check if script execution permissions are disabled for that location.Affected if Script execution is allowed in the upload directory or no execution restrictions are configured.
If the Chinasea Qb Smart Service Robot is deployed with accessible file upload functionality that lacks proper magic byte validation, special character sanitization, and script execution restrictions, the environment is likely affected by this CVE.
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 dataImplement strict server-side file type validation using magic bytes/file signatures, whitelist allowed extensions, sanitize special characters in filenames and paths, store uploads outside the webroot, and disable script execution in upload directories.
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-44164 — 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-2021-44164 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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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.
- 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