CVE-2026-84803EPSS p34.8%

CVE-2026-84803CVE-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.

Scoring

CVSS 9.0 ()
VectorCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H
EPSS0.43% probability of exploitation · percentile 34.8% · 2026-10-05T12:00:23Z
Last modified2026-09-02
Sourced from NVD + FIRST.org EPSS. Curated for EU compliance use cases by Adam Lundqvist, Founder at SQUR.