CVE-2021-23836

Name: CVE-2021-23836
Creator: NVD / NIST
Published: 2021-01-15T07:15:14.033+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 4.8/10EPSS 0.92%

Last modified Jun 17, 2026

CVE-2021-23836 is a medium-severity vulnerability rated 4.8/10 on the CVSS scale. An issue was discovered in flatCore before 2.0.0 build 139. A stored XSS vulnerability was identified in the prefs_smtp_psw HTTP request body parameter for the acp interface. EPSS estimates a 0.92% chance of exploitation in the next 30 days.

Description

An issue was discovered in flatCore before 2.0.0 build 139. A stored XSS vulnerability was identified in the prefs_smtp_psw HTTP request body parameter for the acp interface. An admin user can inject malicious client-side script into the affected parameter without any form of input sanitization. The injected payload will be executed in the browser of a user whenever one visits the affected module page.

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

0.92%

55.7th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-79

Affected Software

Vendor	Product	Versions
Flatcore	Flatcore	<= 2.0.0

References

http://packetstormsecurity.com/files/160936/flatCore-CMS-XSS-File-Disclosure-SQL-Injection.htmlExploit, Third Party Advisory, VDB Entry
https://github.com/flatCore/flatCore-CMSProduct, Third Party Advisory
https://sec-consult.com/vulnerability-lab/Third Party Advisory
http://packetstormsecurity.com/files/160936/flatCore-CMS-XSS-File-Disclosure-SQL-Injection.htmlExploit, Third Party Advisory, VDB Entry
https://github.com/flatCore/flatCore-CMSProduct, Third Party Advisory
https://sec-consult.com/vulnerability-lab/Third Party Advisory

Timeline

Published: Jan 15, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-23836?

How severe is CVE-2021-23836?

CVE-2021-23836 has a CVSS score of 4.8/10 (MEDIUM severity). The EPSS model estimates a 0.92% probability of exploitation in the next 30 days.

How do I fix CVE-2021-23836?

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-2021-23836?

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

Scan your code now

Source: NVD / NIST