Flask ReuploadedApplication · Jugmac00
CVE-2026-27641
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 · uneditedFlask-Reuploaded provides file uploads for Flask. A critical path traversal and extension bypass vulnerability in versions prior to 1.5.0 allows remote attackers to achieve arbitrary file write and remote code execution through Server-Side Template Injection (SSTI). Flask-Reuploaded has been patched in version 1.5.0. Some workarounds are available. Do not pass user input to the `name` parameter, use auto-generated filenames only, and implement strict input validation if `name` must be used.
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 confidenceFlask-Reuploaded versions before 1.5.0 contain a critical path traversal and extension bypass vulnerability that allows remote attackers to write arbitrary files to the filesystem and achieve remote code execution via Server-Side Template Injection (SSTI) by manipulating the 'name' parameter in file upload operations.
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
Flask ReuploadedApplication
< 1.5.0CVSS 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
- 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 Flask-Reuploaded is installedRun 'pip show flask-reuploaded' or check your requirements.txt/dependencies for the 'flask-reuploaded' packageAffected if The package is present in your environment
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Determine the installed versionCheck the version field from 'pip show flask-reuploaded' output, or grep for 'flask-reuploaded' in your lock/requirements fileAffected if The version is lower than 1.5.0 or no specific version is pinned (implying an older release is in use)
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Locate file upload code using Flask-ReuploadedSearch your codebase for imports of 'fluploaded' or 'UploadSet' and review upload handler functions that accept file uploadsAffected if Your application uses Flask-Reuploaded's UploadSet for file handling
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Inspect if the 'name' parameter accepts user inputReview your upload handler code: look for request.form['name'], request.args['name'], or any user-controlled input passed to the upload function's 'name' argumentAffected if User-supplied input from the request is directly used as the 'name' parameter in upload calls
You are affected if Flask-Reuploaded version is below 1.5.0 AND your application uses the library with user-controlled input in the 'name' parameter for file uploads.
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.
dbcve · scoped1.5.0
Upgrade Flask-Reuploaded to version 1.5.0 or later. If upgrading is not immediately possible, ensure user input is never passed directly to the 'name' parameter—use auto-generated filenames exclusively—and implement strict input validation for any unavoidable user-supplied filenames.
1.5.0
- Upgrade Flask-Reuploaded to version 1.5.0 or later using your package manager (e.g., pip install flask-reuploaded==1.5.0)
- After upgrading, verify that user input is never directly passed to the `name` parameter when handling file uploads
- If you must use custom filenames, ensure they are auto-generated or subjected to strict input validation before use
- Test the file upload functionality to confirm the path traversal and extension bypass vulnerabilities are mitigated
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Flask Reuploaded
Scoped from the published advisory
- Consultation3.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,408.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-27641 — 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-2026-27641 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
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