CVE-2026-84803

CriticalCVSS 9.0/10Last modified Sep 2, 2026

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 3.1 9.0/10CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H

Weakness enumeration

Affected software

No affected versions have been published.

Timeline

Published
Sep 2, 2026
Last modified
Sep 2, 2026
NVD status
Deferred

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CVE-2026-84803: Critical severity, CVSS 9.0 | Vulnix