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CVE-2026-84803 Details

ANALYZED

This CVE record has been analyzed and enriched by NVDAPI.com as an independent party.

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.

Metrics

CVSS 3.x Severity and Vector Strings:

VolerionCVSS-B:7.6 HIGHVector:CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:L/A:N

CNA: [email protected]CVSS-B:9 CRITICALVector:CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H

References to Advisories, Solutions, and Tools

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URL	Source(s)	Tag(s)
https://github.com/siyuan-note/siyuan/security/advisories/GHSA-7h8j-qw37-w46g	CISA-ADP	AdvisoryExploitRemedyVendor
https://github.com/siyuan-note/siyuan/security/advisories/GHSA-7h8j-qw37-w46g	[email protected]	AdvisoryExploitRemedyVendor
https://www.vulncheck.com/advisories/siyuan-before-3.8.2-stored-xss-via-incomplete-asset-blocklist	[email protected]	Advisory

Weakness Enumeration

CWE-ID	CWE Name	Source
CWE-79	Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')	[email protected]

Affected Products

Product	Versions
SiYuan	<= 3.8.1 (semver)
CPE cpe:2.3:a:b3log:siyuan:::::::: Remediation Upgrade: v3.8.2moderate effort

Change History

2 change records found show changes

Date	Action	Recorded By
Sep 2, 2026	CVE Modified	CISA-ADP
Sep 2, 2026	New CVE Received	[email protected]