CVE-2026-27641

Impact

### Impact A critical path traversal and extension bypass vulnerability in Flask-Reuploaded allows remote attackers to achieve arbitrary file write and remote code execution through Server-Side Template Injection (SSTI). ### Patches Flask-Reuploaded has been patched in version 1.5.0 ### Workarounds 1. **Do not pass user input to the `name` parameter** 2. Use auto-generated filenames only 3. Implement strict input validation if `name` must be used ```python from werkzeug.utils import secure_filename import os # Sanitize user input before passing to save() safe_name = secure_filename(request.form.get('custom_name')) # Remove path separators safe_name = os.path.basename(safe_name) # Validate extension matches policy if not photos.extension_allowed(photos.get_extension(safe_name)): abort(400) filename = photos.save(file, name=safe_name) ``` ### Resources The fix is documented in the pull request, see https://github.com/jugmac00/flask-reuploaded/pull/180. A proper write-up was created by the reporter of the vulnerability, Jaron Cabral (https://www.linkedin.com/in/jaron-cabral-751994357/), but is not yet available as of time of this publication.

Affected packages

Affected products

Weakness classification

References

• NVD record
• CVE.org record
• GitHub advisory
• https://github.com/advisories/GHSA-65mp-fq8v-56jr
• https://github.com/jugmac00/flask-reuploaded/security/advisories/GHSA-65mp-fq8v-56jr
• https://nvd.nist.gov/vuln/detail/CVE-2026-27641
• https://github.com/jugmac00/flask-reuploaded/pull/180
• https://github.com/jugmac00/flask-reuploaded/commit/d64c6b2f71cb73734fc38baa0e3e156926361288
• https://github.com/pypa/advisory-database/tree/main/vulns/flask-reuploaded/PYSEC-2026-341.yaml
• https://pypi.org/project/flask-reuploaded