CVE-2021-20729

Name: CVE-2021-20729
Creator: NVD / NIST
Published: 2022-03-31T08:15:08.13+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.1/10EPSS 2.77%

Last modified Jun 17, 2026

CVE-2021-20729 is a medium-severity vulnerability rated 6.1/10 on the CVSS scale. Cross-site scripting vulnerability in pfSense CE and pfSense Plus (pfSense CE software versions 2.5.2 and earlier, and pfSense Plus software versions 21.05 and earlier) allows a remote attacker to inject an arbitrary script via a malicious URL.. EPSS estimates a 2.77% chance of exploitation in the next 30 days.

Description

Cross-site scripting vulnerability in pfSense CE and pfSense Plus (pfSense CE software versions 2.5.2 and earlier, and pfSense Plus software versions 21.05 and earlier) allows a remote attacker to inject an arbitrary script via a malicious URL.

Metrics

CVSS 3.1

6.1/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

EPSS Probability

2.77%

84.4th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-79

Affected Software

Vendor	Product	Versions
Netgate	Pfsense Plus	<= 21.05
Pfsense	Pfsense	<= 2.5.2

References

https://docs.netgate.com/downloads/pfSense-SA-21_02.captiveportal.ascThird Party Advisory
https://jvn.jp/en/jp/JVN87751554/index.htmlThird Party Advisory, VDB Entry
https://docs.netgate.com/downloads/pfSense-SA-21_02.captiveportal.ascThird Party Advisory
https://jvn.jp/en/jp/JVN87751554/index.htmlThird Party Advisory, VDB Entry

Timeline

Published: Mar 31, 2022
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-20729?

How severe is CVE-2021-20729?

CVE-2021-20729 has a CVSS score of 6.1/10 (MEDIUM severity). The EPSS model estimates a 2.77% probability of exploitation in the next 30 days.

How do I fix CVE-2021-20729?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-20729?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST