Resource exhaustion in Siyuan-Note Siyuan
CVE-2026-74903
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.
Vulnerability class: DoS (Denial of Service)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N.
EPSS exploit prediction
EPSS: 0.003 (19.4th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 19th percentile — 19.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.001
Affected products
Weakness classification (CWE)
References
- github.com/siyuan-note/siyuan/security/advisories/GHSA-3j8q-5c8c-grwm (vendor-advisory)
- www.vulncheck.com/advisories/siyuan-before-insufficient-access-control-via-spin… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-74903?
- CVE-2026-74903 is a medium-severity vulnerability in Siyuan-Note Siyuan, classified under Uncontrolled Resource Consumption. CVSS score: 4.3/10. Published 2026-08-18.
- How severe is CVE-2026-74903?
- Medium severity. CVSS v3 base score is 4.3 out of 10.