---
title: "CVE-2026-27641: Flask-Reuploaded vulnerable to Remote Code Execution via Server-Side Template Injection"
url: https://erroneo.us/security/cve/CVE-2026-27641/
description: "CVE-2026-27641 (flask-reuploaded (PyPI)): Flask-Reuploaded provides file uploads for Flask. A critical path traversal and extension bypass vulnerability in…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-02-25
date_modified: 2026-02-27
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-27641"
kev: false
cvss: 9.8
epss: 0.01266
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-27641: Flask-Reuploaded vulnerable to Remote Code Execution via Server-Side Template Injection

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- 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.

## Affected packages

- PyPI `flask-reuploaded` < 1.5.0 → fixed: 1.5.0

## Affected products (CVE record)

- jugmac00 flask-reuploaded: < 1.5.0

## Severity

- GitHub_M CVSS 3.1: 9.8 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`
- GitHub CVSS 3.1: 9.8 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`

## Exploitation

- 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.

## Sources

- [GitHub Advisory GHSA-65mp-fq8v-56jr](https://github.com/advisories/GHSA-65mp-fq8v-56jr)
- [CVE.org record CVE-2026-27641](https://www.cve.org/CVERecord?id=CVE-2026-27641)
- [NVD entry CVE-2026-27641](https://nvd.nist.gov/vuln/detail/CVE-2026-27641)
- [github.com](https://github.com/jugmac00/flask-reuploaded/security/advisories/GHSA-65mp-fq8v-56jr)
- [github.com](https://github.com/jugmac00/flask-reuploaded/pull/180)
- [github.com](https://github.com/jugmac00/flask-reuploaded/commit/d64c6b2f71cb73734fc38baa0e3e156926361288)

---
Source page: https://erroneo.us/security/cve/CVE-2026-27641/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt