Description
SiYuan before v3.8.2 contains a stored cross-site scripting vulnerability in asset serving due to an incomplete extension blocklist that misses script-capable file types. Attackers can upload files with extensions like .xht, .ehtml, .xsl, .xbl, or .rdf that resolve to executable media types and execute JavaScript to steal API tokens and compromise workspaces.
Published: 2026-09-02
Score: 8.6 High
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories

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History

Wed, 02 Sep 2026 10:45:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Wed, 02 Sep 2026 11:30:00 +0000

Type Values Removed Values Added
Description SiYuan before v3.8.2 contains a stored cross-site scripting vulnerability in asset serving due to an incomplete extension blocklist that misses script-capable file types. Attackers can upload files with extensions like .xht, .ehtml, .xsl, .xbl, or .rdf that resolve to executable media types and execute JavaScript to steal API tokens and compromise workspaces.
Title SiYuan before v3.8.2 Stored XSS via incomplete asset blocklist
First Time appeared B3log
B3log siyuan
Weaknesses CWE-79
CPEs cpe:2.3:a:b3log:siyuan:*:*:*:*:*:*:*:*
Vendors & Products B3log
B3log siyuan
References
Metrics cvssV3_1

{'score': 9, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H'}

cvssV4_0

{'score': 8.6, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N'}

Subscriptions

B3log Siyuan
cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published:

Updated: 2026-09-02T13:54:45.797Z

Reserved: 2026-09-02T10:19:32.991Z

Link: CVE-2026-84803

cve-icon Vulnrichment

Updated: 2026-09-02T13:54:25.022Z

cve-icon NVD

Status : Deferred

Published: 2026-09-02T12:17:17.183

Modified: 2026-09-02T14:17:17.443

Link: CVE-2026-84803

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-09-02T13:15:06Z

Weaknesses
  • CWE-79

    Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')