Auth bypass in Siyuan-Note Siyuan
CVE-2026-85579
SiYuan is affected by an information disclosure vulnerability (confirmed in v3.8.1, fixed in v3.8.2) in the reader-accessible POST /api/transactions/undoState endpoint. The endpoint returns the peekMutatedRootIDs list from the global undo-log stack for a caller-supplied root ID without applying publish-access visibility filtering. An authenticated reader who knows the root ID of a visible document can obtain the internal root IDs of other documents (including private or unpublished ones) modified in the same cross-document transaction, disclosing internal identifiers and cross-document relationships. Document body contents are not directly exposed.
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 (19.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 19th percentile — 19.3% 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-6gf8-q9ch-w732 (vendor-advisory)
- www.vulncheck.com/advisories/siyuan-before-3.8.2-information-disclosure-via-und… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-85579?
- CVE-2026-85579 is a medium-severity vulnerability in Siyuan-Note Siyuan, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 4.3/10. Published 2026-09-04.
- How severe is CVE-2026-85579?
- Medium severity. CVSS v3 base score is 4.3 out of 10.