CVE-2026-74902 SiYuan before v3.7.4 XSS-to-RCE via malicious filename upload
Attackers can execute arbitrary OS commands by tricking users into uploading files with malicious filenames containing script payloads.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-74902?
CVE-2026-74902 is a critical cross-site scripting vulnerability in siyuan-note siyuan, published on 18 Aug 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
SiYuan before v3.7.4 contains a cross-site scripting vulnerability in the file upload validation flow that fails to escape filenames before inserting them into HTML via insertAdjacentHTML. Attackers can craft a malicious filename containing script payloads that execute with full OS command access when a user drags, drops, or pastes the file into the editor.
Weakness: CWE-79
Which versions are affected by CVE-2026-74902?
How do I fix CVE-2026-74902?
No fix has been published for CVE-2026-74902 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-2026-74902 being exploited?
There is no known exploitation of CVE-2026-74902 in the wild and no public exploit code.
Sources
Also known as GHSA-jwj6-pgg9-m3v5.