CVE-2026-85579: SiYuan before v3.8.2 Information Disclosure via undoState

Severity: medium (CVSS 4.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-04 · updated 2026-09-08
Weakness: CWE-639

Description

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who knows the root ID of a visible document can obtain the internal root IDs of other documents (including private or unpublished ones) modified in the same cross-document transaction, disclosing internal identifiers and cross-document relationships.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.

Affected products

siyuan-note siyuan: before 3.8.2 — fixed in 3.8.2

How to fix

Upgrade to a fixed version: siyuan-note siyuan 3.8.2. Check the vendor advisory for mitigations.

References

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