CVE-2026-27641: Flask-Reuploaded provides file uploads for Flask

This week

CRITICAL 9.8REMOTEUPGRADE

CVE-2026-27641 is a critical-severity flaw (CVSS 9.8) affecting flask-reuploaded. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 st

Why this priority

Critical severity
Public exploit reference
CISA SSVC: automatable with total technical impact
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.3% (top 29%)
CISA exploited list	No
Weakness	CWE-1336, CWE-22
Published	2026-02-25
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: jugmac00

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-02-25 04:16 UTCPublished CVE record published
2026-06-17 10:27 UTCUpdated Record last modified

jugmac00 flask-reuploaded UPGRADE

Affected: < 1.5.0

Fixed in: 1.5.0

Safe to downgrade to: no unaffected older release

1. Check installed version

pip show flask-reuploaded

2. UPGRADE to 1.5.0

pip install --upgrade "flask-reuploaded>=1.5.0"

Exact fixes by distribution

Python (pip) · flask-reuploaded · FIXED · 1.5.0 · vulnerable: < 1.5.0 · source

pip install --upgrade "flask-reuploaded>=1.5.0" pip show flask-reuploaded

Fedora 46 · python-configargparse · FIXED · 1.9.0-1.fc46 · FEDORA-2026-3ab7c44443 · source

sudo dnf upgrade --advisory=FEDORA-2026-3ab7c44443

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

GitHub PoC: Max78000/CVE-2026-27641-Flask-Reuploaded (0 stars)

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-27641?

flask-reuploaded: upgrade to 1.5.0. Exact commands for each OS are on this page.

Is CVE-2026-27641 being exploited?

CVE-2026-27641 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-27641 affect?

CVE-2026-27641 affects flask-reuploaded. Severity is critical (CVSS 9.8). 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

How urgent is CVE-2026-27641?

Priority 65/100. Critical severity; Public exploit reference; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action

Software pages

Flask vulnerabilities

References

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