What is CVE-2021-43421?

CVE-2021-43421 is a critical-severity vulnerability in Std42 Elfinder, classified under Unrestricted Upload of File with Dangerous Type. CVSS score: 9.8/10. Published 2022-04-07.

How severe is CVE-2021-43421?

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

Is CVE-2021-43421 known to be exploited?

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

Arbitrary file upload in Std42 Elfinder

CVE-2021-43421

A File Upload vulnerability exists in Studio-42 elFinder 2.0.4 to 2.1.59 via connector.minimal.php, which allows a remote malicious user to upload arbitrary files and execute PHP code.

Vulnerability class: Unrestricted File Upload

Published 2022-04-07 · 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: 0.428 (98.7th percentile), scored 2026-09-28.

Moderate probability of exploitation in the next 30 days — watch for active exploitation reports. 99th percentile — 98.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.428 · newest: 0.428 · change: 0.000

Affected products

Std42 Elfinder

Weakness classification (CWE)

CWE-434 — Unrestricted Upload of File with Dangerous Type

Public proof-of-concept exploits

References

github.com/Studio-42/elFinder/issues/3429 (Exploit, Third Party Advisory, Issue Tracking)
twitter.com/infosec_90/status/1455180286354919425 (Third Party Advisory)

Frequently asked questions

What is CVE-2021-43421?: CVE-2021-43421 is a critical-severity vulnerability in Std42 Elfinder, classified under Unrestricted Upload of File with Dangerous Type. CVSS score: 9.8/10. Published 2022-04-07.
How severe is CVE-2021-43421?: Critical severity. CVSS v3 base score is 9.8 out of 10.
Is CVE-2021-43421 known to be exploited?: 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.