CVE-2026-74903 SiYuan before v3.7.4 Insufficient Access Control via spinBlockDOM
Authenticated non-admin users can access a privileged API endpoint, causing denial of service via resource starvation and bypassing intended role restrictions.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-74903?
CVE-2026-74903 is a medium-severity missing authorization vulnerability in siyuan-note siyuan, published on 18 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
SiYuan before v3.7.4 contains an insufficient access control vulnerability in the /api/lute/spinBlockDOM endpoint, which is guarded only by CheckAuth middleware instead of CheckAdminRole like its sibling endpoint. Authenticated users with RoleEditor or RoleReader roles can invoke the endpoint to transform arbitrary DOM input, and large payloads cause endpoint starvation through per-path mutex serialization.
Weakness: CWE-400
Which versions are affected by CVE-2026-74903?
How do I fix CVE-2026-74903?
No fix has been published for CVE-2026-74903 yet. Limit exposure of the affected software until one is available.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-74903 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-74903 exists.
Sources
Also known as GHSA-rm42-2qwv-9xcq.