SiYuan before v3.8.2 Information Disclosure via undoState

published 2026-09-04 2 mo ago modified 2026-09-08 2 mo ago also EUVD-2026-71002

cvss: 4.3; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.3%; EPSS 0.3% chance of exploitation in 30 days, percentile 20%
public exploits: 0; none known

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who knows the root ID of a visible document can obtain the internal root IDs of other documents (including private or unpublished ones) modified in the same cross-document transaction, disclosing internal identifiers and cross-document relationships.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

Patch / fix

fixed in 1

siyuan-note siyuan 3.8.2

CISA SSVC

Exploitation: Proof of concept is public
Automatable: no
Technical impact: partial
Assessed: 2 mo ago (2026-09-08)

Exploit prediction

0.28% chance of exploitation in the next 30 days, higher than 20% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/siyuan-note/siyuan/security/advisories/GHSA-6gf8-q9ch-w732 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	4.0	5.3	CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
CNA	3.1	4.3	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
CNA	4.0	5.3	CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected products

siyuan-note siyuan

Classification

Weakness

CWE-639 Authorization Bypass Through User-Controlled Key

References

github.com /siyuan-note/siyuan/security/advisories/GHSA-6gf8-q9ch-w732
vendor-advisory, exploit
vulncheck.com /advisories/siyuan-before-3.8.2-information-disclosure-via-undostate
third-party-advisory

Sources

CVE List CVE-2026-85579
NVD CVE-2026-85579

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary