siyuan-note SiYuan up to 3.7.3 SSRF Protection kernel/util/net.go isPrivateIP server-side request forgery

Summaryinfo

A vulnerability described as problematic has been identified in siyuan-note SiYuan up to 3.7.3. Impacted is the function isPrivateIP of the file kernel/util/net.go of the component SSRF Protection. Such manipulation leads to server-side request forgery. This vulnerability is referenced as CVE-2026-74905. It is possible to launch the attack remotely. No exploit is available.

Detailsinfo

A vulnerability was found in siyuan-note SiYuan up to 3.7.3 and classified as problematic. Affected by this issue is the function isPrivateIP of the file kernel/util/net.go of the component SSRF Protection. The manipulation with an unknown input leads to a server-side request forgery vulnerability. Using CWE to declare the problem leads to CWE-918. The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination. Impacted is confidentiality. CVE summarizes:

SiYuan before v3.7.4 contains a server-side request forgery (SSRF) vulnerability in the isPrivateIP function in kernel/util/net.go, used by SSRFSafeDialer to enforce SSRF protection in SafeMode. The function only checks for loopback, link-local unicast, private, and unspecified addresses and does not recognize IPv6 transition addresses (NAT64 64:ff9b::/96, 6to4 2002::/16, Teredo 2001::/32) that embed private IPv4 destinations. When SafeMode is enabled, an authenticated attacker can bypass the SSRF guard via the network forward proxy, WebSocket proxy, or SSE proxy endpoints by supplying a URL whose hostname resolves to such a transition address, reaching internal services and cloud metadata endpoints (e.g., 169.254.169.254). Because the forward proxy returns the full response body, this is a full-read SSRF that can be used to steal instance credentials, reach internal services, and port-scan internal infrastructure.

The advisory is available at github.com. This vulnerability is handled as CVE-2026-74905 since 08/17/2026. The exploitation is known to be easy. The attack may be launched remotely. Technical details are known, but there is no available exploit.

Upgrading to version 3.7.4 eliminates this vulnerability.

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Productinfo

Vendor

• siyuan-note

Name

• SiYuan

Version

• 3.7.0
• 3.7.1
• 3.7.2
• 3.7.3

Website

• Product: https://github.com/siyuan-note/siyuan/

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