CVE-2021-42338
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 · unedited4MOSAn GCB Doctor’s login page has improper validation of Cookie, which allows an unauthenticated remote attacker to bypass authentication by code injection in cookie, and arbitrarily manipulate the system or interrupt services by upload and execution of arbitrary files.
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 4MOSAn GCB Doctor's login page has improper cookie validation that allows unauthenticated attackers to bypass authentication through cookie-based code injection. This can lead to arbitrary file upload and execution, enabling full system compromise.
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<= 20210708CVSS 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 4mosan Gcb Doctor is installedSearch the system for files or services related to 'Gcb Doctor', '4mosan', or check running web services on common ports (80, 443, 8080) that may host this applicationAffected if The application is found running on the system
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Determine the installed versionLocate version information in the application directory, configuration files, or the login page source code (check for version strings, build dates, or '20210708' and earlier build identifiers)Affected if The version is 20210708 or earlier, or no version is displayed (which may indicate an unpatched older build)
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Verify the login page is accessibleAccess the application's login endpoint (commonly /login, /admin, or the root path) and inspect if it accepts cookie-based authenticationAffected if The login page is reachable and processes authentication requests
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Check for improper cookie validationReview the authentication logic in the application's source code, specifically examining how cookies are validated in login scripts or session handlersAffected if Cookie values are not properly validated server-side or can be manipulated to bypass authentication
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Inspect for unauthorized file upload functionalitySearch the web root for unexpected PHP, ASP, or other script files that may indicate successful exploitation, and check access logs for unusual POST requests to upload endpointsAffected if Suspicious script files exist in the web directory or logs show unauthorized file uploads
A system is affected if 4mosan Gcb Doctor version 20210708 or earlier is running and the login page with vulnerable cookie validation is accessible.
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 proper server-side validation of all cookie values, enforce robust authentication mechanisms, and validate/sanitize all file upload inputs before processing.
- Consultation8.0 h
- Implementation24.0 h
- Testing12.0 h
- Review / QA6.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $14,080.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-42338 — 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-2021-42338 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