CVE-2026-84803

EUVD-2026-69915
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.
Cross-site Scripting
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTPrimary
9 CRITICAL
NETWORK
LOW
LOW
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H
Awaiting analysis
This vulnerability is currently awaiting analysis.
Base Score
CVSS 3.x
EPSS Score
Percentile: Unknown
Common Weakness Enumeration
References
https://github.com/siyuan-note/siyuan/security/advisories/GHSA-7h8j-qw37-w46g
https://www.vulncheck.com/advisories/siyuan-before-3.8.2-stored-xss-via-incomplete-asset-blocklist
https://github.com/siyuan-note/siyuan/security/advisories/GHSA-7h8j-qw37-w46g