How severe is CVE-2026-40322?

CVE-2026-40322 has a CVSS 3.x base score of 9.0, rated critical severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-40322 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (22nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-40322?

CVE-2026-40322 affects B3log Siyuan. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-40322?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

Does CVE-2026-40322 have an EU (EUVD) identifier?

Yes. CVE-2026-40322 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-23330.

When was CVE-2026-40322 published?

CVE-2026-40322 was published on 2026-04-16 and last updated on 2026-06-17.

CVE-2026-40322

CVE-2026-40322 is a critical-severity vulnerability in B3log Siyuan with a CVSS 3.x base score of 9.0. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-79.

Key facts

Severity: Critical (CVSS 3.x base score 9.0)
EPSS exploit prediction: 0% (22nd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-23330
Weakness: CWE-79
Affected product: B3log Siyuan
Published: 2026-04-16
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2026-40322?: 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.
How severe is CVE-2026-40322?: CVE-2026-40322 has a CVSS 3.x base score of 9.0, rated critical severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-40322 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (22nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-40322?: CVE-2026-40322 affects B3log Siyuan. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-40322?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2026-40322 have an EU (EUVD) identifier?: Yes. CVE-2026-40322 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-23330.
When was CVE-2026-40322 published?: CVE-2026-40322 was published on 2026-04-16 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:b3log:siyuan:*:*:*:*:*:*:*:*

More vulnerabilities in B3log Siyuan

CVE-2026-32938 — Critical (CVSS 9.9): SiYuan is a personal knowledge management system. In versions 3.6.0 and below, the /api/lute/html2BlockDOM on the…
CVE-2026-33670 — Critical (CVSS 9.8): SiYuan is a personal knowledge management system. Prior to version 3.6.2, the /api/file/readDir interface was used to…
CVE-2026-33669 — Critical (CVSS 9.8): SiYuan is a personal knowledge management system. Prior to version 3.6.2, document IDs were retrieved via the…
CVE-2026-32767 — Critical (CVSS 9.8): SiYuan is a personal knowledge management system. Versions 3.6.0 and below contain an authorization bypass…
CVE-2024-55660 — Critical (CVSS 9.8): SiYuan is a personal knowledge management system. Prior to version 3.1.16, SiYuan's `/api/template/renderSprig`…
CVE-2024-53507 — Critical (CVSS 9.8): A SQL injection vulnerability was discovered in Siyuan 3.1.11 in /getHistoryItems.

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