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CVE-2026-40322

B3log Siyuan code injection

9.0 CRITICALEPSS 0.53%
  1. Published16 Apr 2026

Description

SiYuan is an open-source personal knowledge management system. In versions 3.6.3 and below, Mermaid diagrams are rendered with securityLevel set to "loose", and the resulting SVG is injected into the DOM via innerHTML. This allows attacker-controlled javascript: URLs in Mermaid code blocks to survive into the rendered output. On desktop builds using Electron, windows are created with nodeIntegration enabled and contextIsolation disabled, escalating the stored XSS to arbitrary code execution when a victim opens a note containing a malicious Mermaid block and clicks the rendered diagram node. This issue has been fixed in version 3.6.4.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredLow
User interactionRequired
ScopeChanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H

Affected products

B3log Siyuan< 3.6.4

Remediation

Fixed in
B3log Siyuan≥ 3.6.4

References

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Frequently asked

Is CVE-2026-40322 being actively exploited?

CVE-2026-40322 is not in the CISA KEV catalog. Its EPSS exploit probability is 0.53%.

How severe is CVE-2026-40322?

CVE-2026-40322 has a CVSS 3.1 base score of 9.0, rated critical. EPSS estimates a 0.53% probability of exploitation.

Which products are affected by CVE-2026-40322?

Affected products include B3log Siyuan.

How do I fix CVE-2026-40322?

Upgrade affected software to a fixed version, for example B3log Siyuan 3.6.4 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-40322 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.