What is CVE-2020-21487?

CVE-2020-21487 is a critical-severity vulnerability in Netgate Pfsense, classified under Cross-site Scripting. CVSS score: 9.6/10. Published 2023-04-04.

How severe is CVE-2020-21487?

Critical severity. CVSS v3 base score is 9.6 out of 10.

XSS in Netgate Pfsense

CVE-2020-21487

Cross Site Scripting vulnerability found in Netgate pfSense 2.4.4 and ACME package v.0.6.3 allows attackers to execute arbitrary code via the RootFolder field of acme_certificates.php.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2023-04-04 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.6 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.007 (51.7th percentile), scored 2026-10-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 52nd percentile — 51.7% 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

Netgate Pfsense — versions 2.4.4
Netgate Pfsense Acme Package — versions 0.6.3

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

github.com/pfsense/FreeBSD-ports/commit/a6f443cde51e7fcf17e51f16014d3589253284d8 (Patch)
redmine.pfsense.org/issues/9888 (Patch, Issue Tracking)

Frequently asked questions

What is CVE-2020-21487?: CVE-2020-21487 is a critical-severity vulnerability in Netgate Pfsense, classified under Cross-site Scripting. CVSS score: 9.6/10. Published 2023-04-04.
How severe is CVE-2020-21487?: Critical severity. CVSS v3 base score is 9.6 out of 10.