CVE-2026-82654
Received Received - Intake

SiYuan Reflected XSS via Unescaped Block Fields

Publication date: 2026-08-30

Last updated on: 2026-08-30

Assigner: VulnCheck

Description
SiYuan before v3.8.1 fails to properly escape block name, alias, and memo fields in hint, backlink, and breadcrumb rendering functions. Attackers can set a block's name to contain HTML/script tags that execute when another user views documents referencing or displaying that block.

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Meta Information

Published
2026-08-30
Last Modified
2026-08-30
Generated
2026-08-30
AI Q&A
2026-08-30
EPSS Evaluated
N/A
NVD
CVE-2026-82654
EUVD
EUVD-2026-68240

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
siyuan siyuan to 3.8.1 (exc)
siyuan siyuan From 3.7.4 (inc) to 3.8.1 (exc)

Helpful Resources

Exploitability

CWE
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KEV
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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

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Executive Summary

SiYuan before v3.8.1 has a stored cross-site scripting (XSS) vulnerability due to improper escaping of block names, aliases, and memo fields. Attackers can inject HTML or script tags into these fields, which execute when other users view documents referencing the affected block.

Detection Guidance

Check SiYuan application logs for suspicious block names containing HTML/script tags in hint, backlink, or breadcrumb fields. Inspect rendered HTML output for unescaped content in these areas. No specific commands are provided in the resources.

Impact Analysis

This vulnerability allows attackers to execute malicious scripts in the context of other users' SiYuan sessions. This could lead to unauthorized data access, session hijacking, or defacement of documents. The impact is higher in shared or collaborative environments.

Compliance Impact

This vulnerability could lead to unauthorized data access or modification, violating confidentiality requirements in GDPR and HIPAA. Organizations using SiYuan may face compliance risks if user data is exposed due to this flaw.

Mitigation Strategies
  • Upgrade SiYuan to the latest version if available, as patches may have been released.
  • Temporarily disable or restrict access to shared documents until patched.
  • Monitor for unusual activity in hint lists, backlink panels, or breadcrumbs.
  • Apply manual HTML escaping to block names, aliases, and memos in affected functions.

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