Critical severity9.0NVD Advisory· Published Sep 2, 2026· Updated Sep 2, 2026
CVE-2026-84803
CVE-2026-84803
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.
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
Affected products
1- Range: <3.8.2
Patches
Vulnerability mechanics
References
2News mentions
2- Siyuan Note: Batch of 13 Vulnerabilities Includes Critical XSS and DoS FlawsVypr Intelligence · Sep 5, 2026
- Siyuan Note: Critical XSS & High-Severity Flaws Disclosed Together in BatchVypr Intelligence · Sep 3, 2026