What is CVE-2021-27933?

CVE-2021-27933 is a medium-severity vulnerability in Pfsense, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2021-04-28.

How severe is CVE-2021-27933?

Medium severity. CVSS v3 base score is 6.1 out of 10.

Is CVE-2021-27933 known to be exploited?

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

XSS in Pfsense

CVE-2021-27933

pfSense 2.5.0 allows XSS via the services_wol_edit.php Description field.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2021-04-28 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.266 (98.0th percentile), scored 2026-09-30.

Moderate probability of exploitation in the next 30 days — watch for active exploitation reports. 98th percentile — 98.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.266 · newest: 0.266 · change: 0.000

Affected products

Pfsense — versions 2.5.0

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

Public proof-of-concept exploits

References

seclists.org/fulldisclosure/2021/Apr/61 (mailing-list, Exploit, Mailing List, Third Party Advisory)

Frequently asked questions

What is CVE-2021-27933?: CVE-2021-27933 is a medium-severity vulnerability in Pfsense, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2021-04-28.
How severe is CVE-2021-27933?: Medium severity. CVSS v3 base score is 6.1 out of 10.
Is CVE-2021-27933 known to be exploited?: 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.