What is CVE-2021-36551?

CVE-2021-36551 is a medium-severity vulnerability in Tiki Tikiwiki Cms\/groupware, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2021-10-28.

How severe is CVE-2021-36551?

Medium severity. CVSS v3 base score is 5.4 out of 10.

XSS in Tiki Tikiwiki Cms\/groupware

CVE-2021-36551

TikiWiki v21.4 was discovered to contain a cross-site scripting (XSS) vulnerability in the component tiki-calendar.php. This vulnerability allows attackers to execute arbitrary web scripts or HTML via a crafted payload under the Add Event module.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2021-10-28 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.005 (40.6th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 41st percentile — 40.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: 0.000

Affected products

Tiki Tikiwiki Cms\/groupware — versions 21.4

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

github.com/r0ck3t1973/xss_payload/issues/7 (Exploit, Third Party Advisory, Issue Tracking)

Frequently asked questions

What is CVE-2021-36551?: CVE-2021-36551 is a medium-severity vulnerability in Tiki Tikiwiki Cms\/groupware, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2021-10-28.
How severe is CVE-2021-36551?: Medium severity. CVSS v3 base score is 5.4 out of 10.