CVE-2025-9540 Markup Markdown < 3.20.10 - Contributor+ Stored XSS
Contributors can inject JavaScript via links, enabling stored XSS attacks against other users in the Markup Markdown WordPress plugin.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2025-9540?
CVE-2025-9540 is a medium-severity cross-site scripting vulnerability in Unknown Markup Markdown, published on 22 Sep 2025. An attacker needs administrator access to exploit it, with no action from the victim.
Official description
The Markup Markdown WordPress plugin before 3.20.10 allows links to contain JavaScript which could allow users with the contributor role and above to perform Stored Cross-Site Scripting attacks.
Which versions are affected by CVE-2025-9540?
How do I fix CVE-2025-9540?
No fix has been published for CVE-2025-9540 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-2025-9540 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-9540 exists.
Sources
Also known as GHSA-grj3-2jxj-j529.