CVE-2026-74905 (GCVE-0-2026-74905)

Vulnerability from cvelistv5 – Published: 2026-08-18 11:19 – Updated: 2026-08-19 14:10
VLAI
Title
SiYuan before v3.7.4 SSRF via IPv6 Transition Address Bypass
Summary
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.
Severity
6.9 (Medium)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:L
7.1 (High)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N
SSVC
Exploitation: poc Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-19 14:09 UTC
CWE
  • CWE-918 - Server-Side Request Forgery (SSRF)
Assigner
VulnCheck CNA under the mitre root
CNA scorecard B 84/100 over 6752 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
siyuan-note siyuan Affected: 0 , < 3.7.4 (semver)
Unaffected: 3.7.4 (semver)
    cpe:2.3:a:b3log:siyuan:*:*:*:*:*:*:*:*
Create a notification for this product.
Date Public
2026-08-04 00:00
Show details on NVD website
To clipboard 

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