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

> Remote attackers can achieve arbitrary file write and remote code execution via Server-Side Template Injection in Flask-Reuploaded.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 25 Feb 2026
- **Updated:** 25 Feb 2026
- **Also known as:** GHSA-65mp-fq8v-56jr, PYSEC-2026-341

## What is CVE-2026-27641?

CVE-2026-27641 is a critical code injection vulnerability in jugmac00 flask-reuploaded, published on 25 Feb 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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.

Weakness: CWE-22 (Improper Limitation of a Pathname to a Restricted Directory), CWE-1336 (Improper Neutralization of Special Elements Used in a Template Engine)

## Which versions are affected by CVE-2026-27641?

3 open source packages ship an affected version, including flask-reuploaded. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `flask-reuploaded` | PyPI | All versions | 1.5.0 |
| `flask-reuploaded` | PyPI | All versions | 1.5.0 |
| `flask-reuploaded` | PyPI | All versions | 1.5.0 |

Products: Jugmac00 Flask-Reuploaded.

## How do I fix CVE-2026-27641?

Upgrade flask-reuploaded to 1.5.0 or later.

## Is CVE-2026-27641 being exploited?

There is no known exploitation of CVE-2026-27641 in the wild and no public exploit code.

Public exploit code:

- PoC and test server (github_poc): https://github.com/Max78000/CVE-2026-27641-Flask-Reuploaded

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-27641 and fix it if it is affected.

What it is: CVE-2026-27641 is a critical code injection vulnerability in jugmac00 flask-reuploaded, published on 25 Feb 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-27641 in the wild and no public exploit code.

Affected packages and fixed versions:
- flask-reuploaded (PyPI): affected all versions; fixed in 1.5.0
- flask-reuploaded (PyPI): affected all versions; fixed in 1.5.0
- flask-reuploaded (PyPI): affected all versions; fixed in 1.5.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-27641/ (Markdown: https://insights.sbomify.com/CVE-2026-27641/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-27641
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-27641
- OSV: https://osv.dev/vulnerability/CVE-2026-27641

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-27641/
Summaries are generated and may contain mistakes; the official description above is the record.