CVE-2021-34667

Name: CVE-2021-34667
Creator: NVD / NIST
Published: 2021-08-16T19:15:15.65+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.1/10EPSS 0.90%

Last modified Jun 17, 2026

CVE-2021-34667 is a medium-severity vulnerability rated 6.1/10 on the CVSS scale. The Calendar_plugin WordPress plugin is vulnerable to Reflected Cross-Site Scripting due to the use of `$_SERVER['PHP_SELF']` in the ~/calendar.php file which allows attackers to inject arbitrary web scripts, in versions up to and including 1.0.. EPSS estimates a 0.90% chance of exploitation in the next 30 days.

Description

The Calendar_plugin WordPress plugin is vulnerable to Reflected Cross-Site Scripting due to the use of `$_SERVER['PHP_SELF']` in the ~/calendar.php file which allows attackers to inject arbitrary web scripts, in versions up to and including 1.0.

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

0.90%

54.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Calendar Plugin Project	Calendar Plugin	<= 1.0

References

https://plugins.trac.wordpress.org/browser/calendar-plugin/trunk/calendar.php#L86Exploit, Third Party Advisory
https://www.wordfence.com/vulnerability-advisories/#CVE-2021-34667Exploit, Third Party Advisory
https://plugins.trac.wordpress.org/browser/calendar-plugin/trunk/calendar.php#L86Exploit, Third Party Advisory
https://www.wordfence.com/vulnerability-advisories/#CVE-2021-34667Exploit, Third Party Advisory

Timeline

Published: Aug 16, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-34667?

How severe is CVE-2021-34667?

CVE-2021-34667 has a CVSS score of 6.1/10 (MEDIUM severity). The EPSS model estimates a 0.90% probability of exploitation in the next 30 days.

How do I fix CVE-2021-34667?

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-2021-34667?

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

Scan your code now

Source: NVD / NIST