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.

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)

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.

Affected products

Siyuan-note Siyuan

Weakness classification (CWE)

CWE-639 — Authorization Bypass Through User-Controlled Key

References

disclosure@vulncheck.com (vendor-advisory)
disclosure@vulncheck.com (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.