{"id":"CVE-2026-27641","aliases":["GHSA-65mp-fq8v-56jr","PYSEC-2026-341"],"url":"https://o3.security/vulnerability/CVE-2026-27641","summary":"Flask-Reuploaded vulnerable to Remote Code Execution via Server-Side Template Injection","details":"### Impact\nA 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).\n\n### Patches\nFlask-Reuploaded has been patched in version 1.5.0\n\n### Workarounds\n\n1. **Do not pass user input to the `name` parameter**\n2. Use auto-generated filenames only\n3. Implement strict input validation if `name` must be used\n\n```python\nfrom werkzeug.utils import secure_filename\nimport os\n\n# Sanitize user input before passing to save()\nsafe_name = secure_filename(request.form.get('custom_name'))\n# Remove path separators\nsafe_name = os.path.basename(safe_name)\n# Validate extension matches policy\nif not photos.extension_allowed(photos.get_extension(safe_name)):\n    abort(400)\n    \nfilename = photos.save(file, name=safe_name)\n```\n\n### Resources\nThe fix is documented in the pull request, see https://github.com/jugmac00/flask-reuploaded/pull/180.\n\nA 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.","published":"2026-02-25T03:54:54.391Z","modified":"2026-08-12T03:51:19.240206779Z","cvss":{"score":9.8,"severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"flask-reuploaded","fixedVersion":"1.5.0"}],"fix":{"url":"https://github.com/jugmac00/flask-reuploaded/commit/d64c6b2f71cb73734fc38baa0e3e156926361288","label":"jugmac00/flask-reuploaded@d64c6b2"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/27xxx/CVE-2026-27641.json"},{"type":"ADVISORY","url":"https://github.com/jugmac00/flask-reuploaded/security/advisories/GHSA-65mp-fq8v-56jr"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-27641"},{"type":"FIX","url":"https://github.com/jugmac00/flask-reuploaded/commit/d64c6b2f71cb73734fc38baa0e3e156926361288"},{"type":"FIX","url":"https://github.com/jugmac00/flask-reuploaded/pull/180"},{"type":"PACKAGE","url":"https://github.com/jugmac00/flask-reuploaded"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:19.240206779Z"}}