← Vulnerability feed

Vulnerability record · CVE-2021-23836 · published 15 January 2021

CVE-2021-23836: Flatcore cross-site scripting vulnerability

Flatcore · Flatcore

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.

4.8 CVSS 3.1 Medium EPSS 0.92% · top 41.3% CWE-79 · Cross-site scripting
4.8CVSS 3.1 base score, v2 3.5
0.92%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
6References, 2 tagged exploit
17 Jun 2026Last modified by NVD

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.

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

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
http://packetstormsecurity.com/files/160936/flatCore-CMS-XSS-File-Disclosure-SQL-Injection.html ExploitThird Party AdvisoryVDB Entry
https://github.com/flatCore/flatCore-CMS ProductThird Party Advisory
https://sec-consult.com/vulnerability-lab/ Third Party Advisory
http://packetstormsecurity.com/files/160936/flatCore-CMS-XSS-File-Disclosure-SQL-Injection.html ExploitThird Party AdvisoryVDB Entry
https://github.com/flatCore/flatCore-CMS ProductThird Party Advisory
https://sec-consult.com/vulnerability-lab/ Third Party Advisory

Track CVE-2021-23836 inside VULONE

Watch it alongside the ransomware crews, C2 infrastructure and forum chatter that reference it, query it through the API and pull it into your SIEM over TAXII.

Start free Open in platform

Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

8.8CVE-2019-13961Flatcore cross-site request forgery vulnerabilityA CSRF vulnerability was found in flatCore before 1.5, leading to the upload of arbitrary .php files via acp/core/files.upload-script.php.EPSS 2.3%7.2CVE-2020-17452Flatcore unrestricted file upload vulnerabilityflatCore before 1.5.7 allows upload and execution of a .php file by an admin.EPSS 2.4%7.2CVE-2019-10652Flatcore unrestricted file upload vulnerabilityAn issue was discovered in flatCore 1.4.7. acp/acp.php allows remote authenticated administrators to upload arbitrary .php files, related to the addo…EPSS 7.0%6.5CVE-2021-23837Flatcore sql injection vulnerabilityAn issue was discovered in flatCore before 2.0.0 build 139. A time-based blind SQL injection was identified in the selected_folder HTTP request body …EPSS 1.5%6.1CVE-2017-9451Flatcore cross-site scripting vulnerabilityCross site scripting (XSS) vulnerability in pages.edit_form.php in flatCore 1.4.6 allows remote attackers to inject arbitrary JavaScript via the PATH…EPSS 0.74%5.4CVE-2021-40555Flatcore cross-site scripting vulnerabilityCross site scripting (XSS) vulnerability in flatCore-CMS 2.2.15 allows attackers to execute arbitrary code via description field on the new page crea…EPSS 0.44%4.9CVE-2021-23835Flatcore improper input validation vulnerabilityAn issue was discovered in flatCore before 2.0.0 build 139. A local file disclosure vulnerability was identified in the docs_file HTTP request body p…EPSS 1.7%4.8CVE-2021-23838Flatcore cross-site scripting vulnerabilityAn issue was discovered in flatCore before 2.0.0 build 139. A reflected XSS vulnerability was identified in the media_filter HTTP request body parame…EPSS 0.98%

Source: NIST National Vulnerability Database (record CVE-2021-23836), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.