CVE-2021-47733 CMSimple 5.4 Cross-Site Scripting via HTML Unicode Encoding
Attackers can execute arbitrary JavaScript in victims' browsers by bypassing input filters using HTML Unicode encoding in CMSimple.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2021-47733?
CVE-2021-47733 is a medium-severity cross-site scripting vulnerability in CMSimple, published on 23 Dec 2025. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official description
CMSimple 5.4 contains a cross-site scripting vulnerability that allows attackers to bypass input filtering by using HTML to Unicode encoding. Attackers can inject malicious scripts by encoding payloads like ')-alert(1)// and execute arbitrary JavaScript when victims interact with delete buttons.
Weakness: CWE-79
Which versions are affected by CVE-2021-47733?
It affects 1 product.
Products include Cmsimple Cmsimple.
How do I fix CVE-2021-47733?
No fix has been published for CVE-2021-47733 yet. Limit exposure of the affected software until one is available.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2021-47733 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-47733 exists.
Other vulnerabilities in CMSimple
- CVE-2021-43741 Path traversal in n/a
- CVE-2024-57548 Missing authorization in n/a
- CVE-2021-47734 CMSimple 5.4 Authenticated Local File Inclusion Remote Code Execution
- CVE-2021-47735 CMSimple 5.4 Authenticated Remote Code Execution via Template Editing
- CVE-2024-58280 CMSimple 5.15 Remote Command Execution via Extensions Configuration
Sources
Also known as GHSA-m47r-hm3g-h92f.