CVE-2021-28977: Get-Simple Getsimplecms

Medium severity, CVSS 4.8. EPSS: 0.5% chance of exploitation in the next 30 days.

Cross Site Scripting vulnerability in GetSimpleCMS 3.3.16 in admin/upload.php by adding comments or jpg and other file header information to the content of xla, pages, and gzip files,

Affected products

• Get-Simple Getsimplecms: up to and including 3.3.15

Published 2021-06-23. Last modified 2026-06-17.