CVE-2026-66396 SiYuan before v3.7.2 Stored XSS to RCE via title-img IAL
Attackers with editor permissions can inject scripts into document titles to execute arbitrary code via Node.js when victims view the document.
- 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-2026-66396?
CVE-2026-66396 is a critical cross-site scripting vulnerability in siyuan-note siyuan, published on 27 Jul 2026. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.
Official description
SiYuan before v3.7.2 fails to escape the title-img Individual Attribute List value when rendering Gallery and Kanban cover images, allowing stored cross-site scripting via unescaped style attribute interpolation. Attackers with editor permissions can inject onload handlers that execute arbitrary code in the Electron renderer with full Node.js access when victims open affected documents.
Weakness: CWE-79
Which versions are affected by CVE-2026-66396?
How do I fix CVE-2026-66396?
No fix has been published for CVE-2026-66396 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-2026-66396 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-66396 exists.
Sources
Also known as GHSA-5rxg-wh59-mg34, GHSA-pwp5-qq97-mcqc.