High severity · published Sep 9, 2026
CVE-2026-87811
SiYuan before v3.8.2 Stored XSS via notebook template paths
7.3
CVSS
0.4%
EPSS
No
On KEV
Description
SiYuan before v3.8.2 inserts persisted notebook template paths into HTML input value attributes without proper attribute encoding. Attackers can craft malicious template paths that break out of the attribute context and execute JavaScript when a victim opens notebook configuration, enabling same-origin API requests and application state manipulation.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
Required
Confidentiality
High
Integrity
High
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 30% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
SI
siyuan · siyuan-note
before 3.8.2 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-87811
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-87811
github.com
https://github.com/siyuan-note/siyuan/security/advisories/GHSA-v6wf-r2gr-rrgf
www.vulncheck.com
https://www.vulncheck.com/advisories/siyuan-before-3.8.2-stored-xss-via-notebook-template-paths
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