Critical severity · published Aug 17, 2026
CVE-2026-74800
SiYuan before v3.7.4 Stored XSS via assets endpoint
9.0
CVSS
0.4%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
Required
Confidentiality
High
Integrity
High
Availability
High
Scope
Changed
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 37% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
SI
siyuan · siyuan-note
before 3.7.4 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-74800
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-74800
github.com
https://github.com/siyuan-note/siyuan/security/advisories/GHSA-mjf3-jwmf-r6wf
www.vulncheck.com
https://www.vulncheck.com/advisories/siyuan-before-stored-xss-via-assets-endpoint
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