CVE-2021-39340

Name: CVE-2021-39340
Creator: NVD / NIST
Published: 2021-11-01T21:15:07.807+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 4.8/10EPSS 0.90%

Last modified Jun 17, 2026

CVE-2021-39340 is a medium-severity vulnerability rated 4.8/10 on the CVSS scale. The Notification WordPress plugin is vulnerable to Stored Cross-Site Scripting due to insufficient input validation and sanitization via several parameters found in the ~/src/classes/Utils/Settings.php file which made it possible for attackers with administrative user access to inject arbitrary web scripts, in versions up to and including 7.2.4. This affects multi-site installations where unfiltered_html is disabled for administrators, and sites where unfiltered_html is disabled.. EPSS estimates a 0.90% chance of exploitation in the next 30 days.

Description

The Notification WordPress plugin is vulnerable to Stored Cross-Site Scripting due to insufficient input validation and sanitization via several parameters found in the ~/src/classes/Utils/Settings.php file which made it possible for attackers with administrative user access to inject arbitrary web scripts, in versions up to and including 7.2.4. This affects multi-site installations where unfiltered_html is disabled for administrators, and sites where unfiltered_html is disabled.

Metrics

CVSS 3.1

4.8/10

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

EPSS Probability

0.90%

55.1th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-79

Affected Software

Vendor	Product	Versions
Bracketspace	Notification	<= 7.2.4

References

https://github.com/BigTiger2020/word-press/blob/main/Notification.mdExploit, Third Party Advisory
https://plugins.trac.wordpress.org/browser/notification/tags/7.2.4/src/classes/Utils/Settings.php#L167Patch, Third Party Advisory
https://wordfence.com/vulnerability-advisories/#CVE-2021-39340Third Party Advisory
https://github.com/BigTiger2020/word-press/blob/main/Notification.mdExploit, Third Party Advisory
https://plugins.trac.wordpress.org/browser/notification/tags/7.2.4/src/classes/Utils/Settings.php#L167Patch, Third Party Advisory
https://wordfence.com/vulnerability-advisories/#CVE-2021-39340Third Party Advisory

Timeline

Published: Nov 1, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-39340?

How severe is CVE-2021-39340?

CVE-2021-39340 has a CVSS score of 4.8/10 (MEDIUM severity). The EPSS model estimates a 0.90% probability of exploitation in the next 30 days.

How do I fix CVE-2021-39340?

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-2021-39340?

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

Scan your code now

Source: NVD / NIST