by Kastro
Paper/Archive/CVE-2026-84803

CVE-2026-84803

siyuan-note siyuan — SiYuan before v3.8.2 Stored XSS via incomplete asset blocklist

EPSS 0.4%public exploitCVSS 9.0
critical.is priorityof 100
44
CVSS 9.0 (CNA)9.0 / 10 × 3027.0Not in CISA KEV+300.0EPSS percentile 37.1.371 × 207.4Exploit: SSVC poc+1010.0SSVC exploitation: poc+100.0
Description · from the CVE record

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.

Affected

ProductAffectedFixed inSource
siyuan< 3.8.23.8.2CNA

Scores by source

VulnCheck (CNA)9.0CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H
VulnCheck (CNA)8.6CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
CISA ADPSSVCExploitation: poc · Automatable: no · Technical impact: total

References

exploitgithub.com/siyuan-note/siyuan/security/advisories/GHSA-7h8j-qw37-w46gwriteupvulncheck.com/advisories/siyuan-before-3.8.2-stored-xss-via-incomplete-asset-blocklist