Unrestricted File UploadWeakness · CWE-434

CVE-2025-55383

HIGH · 8.6 CVSS v3.1 Published 2025-08-21
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
95/100
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
Moss before v0.15 has a file upload vulnerability. The "upload" function configuration allows attackers to upload files of any extension to any location on the target server.

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

Moss before v0.15 contains an unrestricted file upload vulnerability in its upload function. Attackers can upload files with arbitrary extensions to any directory on the server, potentially enabling remote code execution if executable files are placed in web-accessible locations.

MitigationUpgrade to Moss v0.15 or later. If immediate upgrade is not feasible, restrict the upload function configuration to whitelist only safe file types and limit upload paths to non-executable directories.

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

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
Low
Availability
Low

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

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 Moss installation and version
    Run 'moss --version' or check the package.json/package-lock.json, requirements.txt, or composer.json if using Moss as a library dependency. For manual installations, check the main binary or library file for a version string.
    Affected if The installed version is any version prior to v0.15 (e.g., v0.14.x, v0.13.x, or no version displayed indicating a pre-release build).
  2. Locate upload function usage
    Search codebase for references to 'upload' function from Moss library, or check the Moss configuration file for upload endpoint definitions (typically in config.yaml, config.json, or similar).
    Affected if The 'upload' function is implemented and accessible in the application without explicit extension validation logic present.
  3. Inspect file extension validation
    Examine the upload handler code: look for allowlist logic restricting file extensions (e.g., '.txt', '.pdf', '.jpg'). Search for any file extension validation before the upload processing occurs.
    Affected if No allowlist or blocklist validation is found, or the validation logic is missing/disabled in the upload function.
  4. Check upload directory restrictions
    Review the upload configuration or code to identify the target directory where uploaded files are stored. Look for path sanitization or directory restriction settings.
    Affected if Files can be written to arbitrary directories outside a designated safe upload folder, or no such restriction is configured.
  5. Verify authentication on upload endpoint
    Check if the upload route/endpoint requires authentication or authorization. Examine middleware, route guards, or access control configurations for the '/upload' or similar path.
    Affected if The upload endpoint is publicly accessible without any authentication or authorization checks.

If Moss version is below v0.15, the upload function is in use, and no extension validation, directory restrictions, or authentication are in place, the environment is affected by this 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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade to Moss v0.15 or later. If immediate upgrade is not feasible, restrict the upload function configuration to whitelist only safe file types and limit upload paths to non-executable directories.

Recommended fix Moderate confidence

v0.15

  1. 1. Identify the current Moss installation and version by checking the binary or application directory
  2. 2. Create a full backup of the current Moss installation including configuration files and data directories
  3. 3. Download Moss v0.15 or the latest stable release from the official GitHub repository
  4. 4. Replace the existing Moss binary/application files with the new version
  5. 5. Restore any custom configuration files from the backup if needed
  6. 6. Restart the Moss service to apply the update
  7. 7. Verify the upgrade was successful by checking the running version matches v0.15 or later
  8. 8. Test that the file upload functionality now properly validates file types and restricts upload locations
Caveat Review release notes for v0.15 to check for any configuration or behavioral changes that may affect existing setups

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

Have this fixed Scoped from the published advisory
  • Consultation4.0 h
  • Implementation2.0 h
  • Testing6.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,420
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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-2025-55383 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
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  • Version or environment caveats, and links to real fixes
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