Security Digest · Vulnerability record
CVE-2026-27641: Flask-Reuploaded vulnerable to Remote Code Execution via Server-Side Template Injection
Flask-Reuploaded provides file uploads for Flask.
CVSS 9.8 Critical EPSS 1.3% · p69
Should you act?
Critical and remotely reachable
No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.
- No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 1.3%, percentile 69: FIRST’s model estimates a 1.3% chance of exploitation activity in the next 30 days, higher than 69% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes
flask-reuploaded(PyPI) < 1.5.0, fixed in 1.5.0. Check your lockfile, including transitive dependencies.
What it is
Flask-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.
From the GitHub advisory
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
Resources The fix is documented in the pull request, see https://github.com/jugmac00/flask-reuploaded/pull/180.
Weakness type: CWE-1336, CWE-22.
Product: flask-reuploaded (PyPI) · Assigned by: GitHub_M · Published: 2026-02-25
Affected and fixed versions
| Ecosystem | Package | Vulnerable | First fixed |
|---|---|---|---|
| PyPI | flask-reuploaded | < 1.5.0 | 1.5.0 |
| Vendor | Product | Affected versions (per CVE record) |
|---|---|---|
| jugmac00 | flask-reuploaded | < 1.5.0 |
Severity scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_M | 3.1 | 9.8 Critical | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| GitHub | 3.1 | 9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
- Attack vector: network (remotely reachable)
- Attack complexity: low
- Privileges required: none (no login)
- User interaction: none
- Scope: unchanged
CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.
Exploitation and urgency
- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none, automatable yes, technical impact total.
- FIRST EPSS (model of 2026-10-21): 1.27% probability of exploitation activity in the next 30 days; percentile 69.
Timeline
- — CVE record last updated
- — CVE record published by GitHub_M
- — GitHub-reviewed advisory GHSA-65mp-fq8v-56jr published (critical)
Sources and references
Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.
Vulnerability records
- GitHub Advisory GHSA-65mp-fq8v-56jr github.com
- CVE.org record CVE-2026-27641 cve.org
- NVD entry CVE-2026-27641 nvd.nist.gov
Other references from the CVE record and advisory
- github.com github.com
- github.com github.com
- github.com github.com