What is the CVSS score of CVE-2026-27641?

CVE-2026-27641 has a CVSS 3.1 base score of 9.8 (Critical). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 0.1%.

Which versions of Flask are affected by CVE-2026-27641?

A critical vulnerability in Flask-Reuploaded allows attackers to execute arbitrary code on affected systems through malicious file uploads, potentially compromising applications and exposing…. A patch is available.

Is there a public PoC exploit available for CVE-2026-27641?

Yes, a public proof-of-concept exploit is available for CVE-2026-27641. Prioritise patching immediately. EPSS: 0.1%.

How to fix or mitigate CVE-2026-27641?

Within 24 hours: Identify all systems and applications using Flask-Reuploaded versions up to 1.5.0 and assess exposure; isolate critical affected systems if patching cannot be completed immediately. Within 7 days: Apply available patches to all affected systems and verify successful deployment across production and non-production environments. Within 30 days: Conduct post-patch validation, review application logs for exploitation attempts, and implement enhanced monitoring for file upload activities.

Flask CVE-2026-27641

CRITICAL

Improper Neutralization of Special Elements Used in a Template Engine (CWE-1336)

2026-02-25 security-advisories@github.com

GHSA-65mp-fq8v-56jr

Flask RCE Path Traversal Flask Reuploaded

9.8

CVSS 3.1 · GitHub Advisory

Severity by source

GitHub Advisory PRIMARY

9.8 CRITICAL

AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Primary rating from GitHub Advisory · only source for this CVE.

CVSS VectorGitHub Advisory

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Analysis Generated

Mar 12, 2026 - 21:55 vuln.today

PoC Detected

Feb 27, 2026 - 18:40 vuln.today

Public exploit code

Patch released

Feb 27, 2026 - 18:40 nvd

Patch available

CVE Published

Feb 25, 2026 - 04:16 nvd

CRITICAL 9.8

Blast Radius

ecosystem impact

† from your stack dependencies † transitive graph · vuln.today resolves 4-path depth

2 pypi packages depend on flask-reuploaded (2 direct, 0 indirect)

Ecosystem-wide dependent count for version 1.5.0.

DescriptionGitHub Advisory

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.

AnalysisAI

Path traversal and extension bypass in Flask-Reuploaded file upload library. Allows uploading files with arbitrary extensions to arbitrary directories. PoC and patch available.