CVE-2026-74800

9.4 criticalEPSS 0.4%

Critical (9.4). EPSS 0.4% chance of exploitation in the next 30 days.

SiYuan before v3.7.4 fails to set Content-Disposition and X-Content-Type-Options headers when serving arbitrary file assets, allowing stored cross-site scripting attacks. Authenticated attackers can upload HTML files as assets and execute scripts with full kernel API access when the workspace owner opens the asset link.

Severity

CVSS 4.0

9.4 critical

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

CVSS 3.1

9.0 critical

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

EPSS: 0.4% chance of exploitation in the next 30 days; higher than 37% of CVEs (scores of 2026-10-31)
CWE: CWE-79
Published: 2026-08-17
Modified: 2026-08-26
Record from: the NVD, synced 2026-10-19

References

https://github.com/siyuan-note/siyuan/security/advisories/GHSA-mjf3-jwmf-r6wf
https://www.vulncheck.com/advisories/siyuan-before-stored-xss-via-assets-endpoint

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