CVE-2026-87809

Siyuan before v3.8.2 Information Disclosure via Export Preview

MEDIUM
6.5
CVSS Score
Published: September 9, 2026 at 11:20 AM UTC
Updated: September 18, 2026 at 06:17 PM UTC
2 products affected across 2 vendorsSiyuanSiyuan

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Severity
MEDIUM6.5
Exploit prediction
EPSS 0.4%
SSVC
No known exploit

Description

Siyuan before v3.8.2 fails to apply publish-access filtering to embedded blocks before rendering in the /api/export/preview and /api/lute/copyStdMarkdown endpoints. Attackers with reader access can retrieve the full rendered content of private, hidden, or publish-disabled blocks by accessing public documents containing embed queries that select those blocks.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 3.8.2
Affected range stops below 3.8.2, so it looks safe — our inference, not a vendor statement
v < 3.8.2
Vendor states this is fixed in 3.8.2 (unaffected)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

6.5MEDIUMVulnCheck
Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusDEFERRED
CWE
CWE-639

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