XSS in Get-Simple Getsimplecms

CVE-2021-47870

GetSimple CMS My SMTP Contact Plugin 1.1.2 suffers from a Stored Cross-Site Scripting (XSS) vulnerability. The plugin attempts to sanitize user input using htmlspecialchars(), but this can be bypassed by passing dangerous characters as escaped hex bytes. This allows attackers to inject arbitrary client-side code that executes in the administrator's browser when visiting a malicious page.

Vulnerability class: XSS (Cross-Site Scripting)

EPSS: 0.002 (13.8th percentile) — read the EPSS interpretation.

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.

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2021-47870?
CVE-2021-47870 is a medium-severity vulnerability in Get-Simple Getsimplecms, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2026-01-21.
How severe is CVE-2021-47870?
Medium severity. CVSS v3 base score is 5.4 out of 10.