CVE-2026-40534 Cross-site scripting in DiskStation Manager (DSM)
Authenticated attackers can exploit XSS in the Video API to read or write limited files when the player is launched.
- 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-2026-40534?
CVE-2026-40534 is a medium-severity cross-site scripting vulnerability in Synology DiskStation Manager (DSM), published on 18 Sep 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official description
An improper neutralization of input during web page generation ('cross-site scripting') vulnerability in Video API in Synology DiskStation Manager (DSM) before 7.2.1-69057-10, 7.2.2-72806-7 and 7.3.2-86009-2 allows remote authenticated users to read or write limited files when the player is launched.
Weakness: CWE-79
Which versions are affected by CVE-2026-40534?
How do I fix CVE-2026-40534?
No fix has been published for CVE-2026-40534 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-2026-40534 being exploited?
There is no known exploitation of CVE-2026-40534 in the wild and no public exploit code.
Sources
Also known as GHSA-mr9f-32f3-48r2.