What is CVE-2021-41566?

CVE-2021-41566 is a critical-severity vulnerability in Tad Tadtools, classified under Unrestricted Upload of File with Dangerous Type. CVSS score: 9.8/10. Published 2021-10-08.

How severe is CVE-2021-41566?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Arbitrary file upload in Tad Tadtools

CVE-2021-41566

The file extension of the TadTools file upload function fails to filter, thus remote attackers can upload any types of files and execute arbitrary code without logging in.

Vulnerability class: Unrestricted File Upload

Published 2021-10-08 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.020 (80.0th percentile), scored 2026-09-29.

Low probability of exploitation in the next 30 days, but still tracked. 80th percentile — 80.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.020 · newest: 0.020 · change: 0.000

Affected products

Tad Tadtools — versions 0
Tadtools Project

Weakness classification (CWE)

CWE-434 — Unrestricted Upload of File with Dangerous Type

References

www.twcert.org.tw/tw/cp-132-5170-83472-1.html (Third Party Advisory)

Frequently asked questions

What is CVE-2021-41566?: CVE-2021-41566 is a critical-severity vulnerability in Tad Tadtools, classified under Unrestricted Upload of File with Dangerous Type. CVSS score: 9.8/10. Published 2021-10-08.
How severe is CVE-2021-41566?: Critical severity. CVSS v3 base score is 9.8 out of 10.