Auth bypass in Siyuan-Note Siyuan
CVE-2026-86191
SiYuan versions before v3.8.2 contain an information disclosure vulnerability in the getAttributeViewKeysByID endpoint that allows publish readers to enumerate private attribute view key definitions without verifying parent database visibility. Attackers can access the endpoint to retrieve complete key schemas including sensitive field names and relation definitions from hidden databases.
Vulnerability class: IDOR (Insecure Direct Object Reference)
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:L/I:N/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-j4qq-w6qx-6839 (vendor-advisory)
- www.vulncheck.com/advisories/siyuan-before-3.8.2-private-attribute-view-key-enu… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-86191?
- CVE-2026-86191 is a medium-severity vulnerability in Siyuan-Note Siyuan, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 4.3/10. Published 2026-09-05.
- How severe is CVE-2026-86191?
- Medium severity. CVSS v3 base score is 4.3 out of 10.