CVE-2025-54856 Cross-site scripting in Movable Type (Cloud Edition)
An attacker with ContentType Management privilege can inject scripts into the Edit ContentData page, leading to arbitrary code execution in victim browsers.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2025-54856?
CVE-2025-54856 is a medium-severity cross-site scripting vulnerability in Six Apart Ltd. Movable Type (Cloud Edition), published on 23 Oct 2025. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.
Official description
Movable Type contains a stored cross-site scripting vulnerability in Edit ContentData page. If crafted input is stored by an attacker with "ContentType Management" privilege, an arbitrary script may be executed on the web browser of the user who accesses Edit ContentData page.
Weakness: CWE-79
Which versions are affected by CVE-2025-54856?
How do I fix CVE-2025-54856?
No fix has been published for CVE-2025-54856 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-2025-54856 being exploited?
There is no known exploitation of CVE-2025-54856 in the wild and no public exploit code.
Sources
Also known as GHSA-4wvq-85hg-6256.