CVE-2026-87813

Deferred Deferred - Pending Action

Stored XSS in SiYuan Search Assets Result List

Publication date: 2026-09-09

Last updated on: 2026-09-09

Assigner: VulnCheck

Description

SiYuan before v3.8.2 contains a stored cross-site scripting vulnerability in the Search Assets result list where asset filenames are interpolated into HTML without escaping. Authenticated attackers can craft asset filenames containing malicious markup that executes JavaScript in the victim's browser when searching assets, enabling same-origin API requests and application state manipulation.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-09-09

Last Modified

2026-09-09

Generated

2026-09-30

AI Q&A

2026-09-10

EPSS Evaluated

2026-09-27

NVD

CVE-2026-87813

EUVD

EUVD-2026-74839

Affected Vendors & Products

Vendor	Product	Version / Range
siyuan	siyuan	to 3.8.2 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
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.

Attack-Flow Graph

Executive Summary

This is a stored cross-site scripting (XSS) vulnerability in SiYuan versions before 3.8.2. Attackers can create asset filenames containing malicious JavaScript code. When users search for assets, the unescaped filenames are rendered as HTML, executing the embedded script in their browser. This allows attackers to perform actions like making same-origin API requests or manipulating application state.

Detection Guidance

To detect this vulnerability, check if your SiYuan instance is running version 3.8.1 or earlier. Inspect asset filenames in the Search Assets result list for any containing HTML or JavaScript code. Look for filenames with event handlers like onerror, onclick, or other malicious markup.

Impact Analysis

If you use SiYuan versions before 3.8.2, an attacker could trick you into searching for assets containing malicious filenames. This could lead to unauthorized actions on your behalf, theft of sensitive data, or session hijacking. The impact depends on your permissions within the application.

Compliance Impact

This vulnerability could lead to data breaches, violating GDPR's integrity and confidentiality requirements or HIPAA's safeguards for protected health information. Unauthorized script execution may expose sensitive data, leading to compliance violations and potential legal consequences.

Mitigation Strategies

Upgrade SiYuan to version 3.8.2 or later immediately. Ensure filenames are properly escaped using methods like escapeHtml(item.name) or DOM construction with textContent. Add regression tests to prevent similar issues.

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