What is CVE-2021-33224?

CVE-2021-33224 is a critical-severity vulnerability in Umbraco Forms, classified under Unrestricted Upload of File with Dangerous Type. CVSS score: 9.8/10. Published 2023-02-24.

How severe is CVE-2021-33224?

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

Is CVE-2021-33224 known to be exploited?

1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Arbitrary file upload in Umbraco Forms

CVE-2021-33224

File upload vulnerability in Umbraco Forms v.8.7.0 allows unauthenticated attackers to execute arbitrary code via a crafted web.config and asp file.

Vulnerability class: Unrestricted File Upload

Published 2023-02-24 · last modified 2026-07-09.

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: 0.007 (52.5th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 53rd percentile — 52.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.007 · newest: 0.007 · change: +0.000

Affected products

Umbraco Forms — versions 8.7.0

Weakness classification (CWE)

CWE-434 — Unrestricted Upload of File with Dangerous Type

Public proof-of-concept exploits

ARPSyndicate/cvemon

References

af854a3a-2127-422b-91ae-364da2661108 (Product)
our.umbraco.com/packages/developer-tools/umbraco-forms (Release Notes)

Frequently asked questions

What is CVE-2021-33224?: CVE-2021-33224 is a critical-severity vulnerability in Umbraco Forms, classified under Unrestricted Upload of File with Dangerous Type. CVSS score: 9.8/10. Published 2023-02-24.
How severe is CVE-2021-33224?: Critical severity. CVSS v3 base score is 9.8 out of 10.
Is CVE-2021-33224 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.