CVE-2026-74905 — HIGH (7.1)

Vulnerability Description

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.

CVSS Score

7.1

HIGH

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

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

LOW

User Interaction

NONE

Scope

UNCHANGED

Confidentiality

HIGH

Integrity

LOW

Availability

NONE

Related Weaknesses (CWE)

CWE-918

References

FAQ

What is CVE-2026-74905?

CVE-2026-74905 is a vulnerability with a CVSS score of 7.1 (HIGH). 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 f...

How severe is CVE-2026-74905?

CVE-2026-74905 has been rated HIGH with a CVSS base score of 7.1/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-74905?

Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.