SiYuan up to 3.6.3 Mermaid cross site scripting

CVSS Meta Temp Score
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CTI Interest Score
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6.2$0-$5k0.00

Summaryinfo

A vulnerability described as problematic has been identified in SiYuan up to 3.6.3. This affects an unknown function of the component Mermaid Handler. Such manipulation leads to cross site scripting. This vulnerability is uniquely identified as CVE-2026-40322. The attack can be launched remotely. No exploit exists. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability was found in SiYuan up to 3.6.3. It has been rated as problematic. Affected by this issue is an unknown code block of the component Mermaid Handler. The manipulation with an unknown input leads to a cross site scripting vulnerability. Using CWE to declare the problem leads to CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. Impacted is integrity. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-40322 since 04/10/2026. The exploitation is known to be easy. The attack may be launched remotely. Successful exploitation requires user interaction by the victim. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1059.007.

Upgrading to version 3.6.4 eliminates this vulnerability. The upgrade is hosted for download at github.com.

The vulnerability is also documented in the vulnerability database at CNNVD (CNNVD-202604-3438). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Name

Version

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.2
VulDB Meta Temp Score: 6.2

VulDB Base Score: 3.5
VulDB Temp Score: 3.4
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 9.0
CNA Vector (GitHub_M): 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Cross site scripting
CWE: CWE-79 / CWE-94 / CWE-74
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: SiYuan 3.6.4

Timelineinfo

04/10/2026 CVE reserved
04/17/2026 +7 days Advisory disclosed
04/17/2026 +0 days VulDB entry created
04/19/2026 +2 days VulDB entry last update

Sourcesinfo

Advisory: GHSA-x63q-3rcj-hhp5
Status: Confirmed

CVE: CVE-2026-40322 (🔒)
GCVE (CVE): GCVE-0-2026-40322
GCVE (VulDB): GCVE-100-357992
CNNVD: CNNVD-202604-3438 - SiYuan 安全漏洞

Entryinfo

Created: 04/17/2026 06:31
Updated: 04/19/2026 22:29
Changes: 04/17/2026 06:31 (65), 04/17/2026 20:28 (6), 04/18/2026 16:25 (1), 04/19/2026 22:29 (1)
Complete: 🔍
Cache ID: 216::103

VulDB is the best source for vulnerability data and more expert information about this specific topic.

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