Medium severity · published Aug 22, 2026
CVE-2026-59809
SiYuan before v3.8.0 Secret Exfiltration via http_request URL
4.9
CVSS
0.4%
EPSS
No
On KEV
Description
SiYuan before v3.8.0 interpolates secret placeholders into the destination URL parameter of the http_request MCP tool, allowing attackers to exfiltrate stored secrets. An MCP client can craft a request with an attacker-controlled URL containing secret placeholders to send plaintext secret values to any public host without confirmation.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N
Attack vector
Network
Complexity
Low
Privileges
High
User interaction
None
Confidentiality
High
Integrity
None
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 35% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
SI
siyuan · siyuan-note
before 3.8.0 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-59809
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-59809
github.com
https://github.com/siyuan-note/siyuan/security/advisories/GHSA-853m-gvvm-6rvx
www.vulncheck.com
https://www.vulncheck.com/advisories/siyuan-before-secret-exfiltration-via-http-request-url
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