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Authorization Bypass (IDOR)Weakness · CWE-639

CVE-2025-3519

HIGH · 7.0 CVSS v4.0 Published 2025-04-22
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
76/100
Remediation priority · High
Remotely reachable 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 authorization bypass in Unblu Spark allows a participant of a conversation to replace an existing, uploaded file. Every uploaded file in Unblu gets assigned with a randomly generated Universally Unique ID (UUID). In case a participant of this or another conversation gets access to such a file ID, it can be used to replace the file without changing the file name and details or the name of the user who uploaded the file. During the upload, file interception and allowed file type rules are still applied correctly.

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

Unblu Spark fails to validate file ownership during replacement operations. Any participant who obtains a file's UUID (from their own or another conversation) can overwrite that file while preserving the original filename, details, and uploader name. The system correctly enforces file type restrictions during upload but lacks authorization checks to verify the requester has permission to modify the existing file.

MitigationImplement ownership and authorization validation before allowing file replacement, ensuring only the original uploader or explicitly authorized users can overwrite existing files.

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
High
Privileges
Low
Authentication
X
User interaction
None
Scope
X

CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

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 Unblu Spark installation and version
    Locate the Unblu Spark application and determine its installed version by checking the application's about page, version file, or startup logs. Common locations include the administration console or configuration files in the installation directory.
    Affected if The installed version cannot be determined or falls within any version range where file ownership validation was not implemented.
  2. Verify file API exposure
    Review the network configuration and API endpoints to confirm whether file upload and replacement endpoints are externally accessible. Check for endpoints that handle file operations (typically under paths containing '/file/', '/upload/', or similar).
    Affected if File operation endpoints are reachable without additional authentication barriers beyond basic session login.
  3. Check for UUID predictability
    Examine how file UUIDs are generated and whether they can be enumerated. Test whether obtaining a UUID from one conversation allows access to file operations in another conversation.
    Affected if File UUIDs are sequential, predictable, or can be accessed across conversation boundaries without authorization validation.
  4. Review file replacement authorization
    Using two different user accounts, attempt to obtain a file UUID from one user's conversation and use it to perform a replacement operation from a different user session. Log all API requests and responses.
    Affected if The file replacement operation succeeds using a UUID from a conversation the requester did not originate, without requiring ownership verification.

A user is affected if Unblu Spark is running and allows file replacement operations using UUIDs from conversations the requester does not own, indicating missing ownership 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.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Implement ownership and authorization validation before allowing file replacement, ensuring only the original uploader or explicitly authorized users can overwrite existing files.

Have this fixed Scoped from the published advisory
  • Consultation6.0 h
  • Implementation12.0 h
  • Testing6.0 h
  • Review / QA4.0 h
28.0 hours of engineering $4,980
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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-2025-3519 in production — separate from our analysis above.

No notes yet

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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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