CVE-2026-74905
SiYuan before v3.7.4 SSRF via IPv6 Transition Address Bypass
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.
INFO
Published Date :
Aug. 18, 2026, 12:19 p.m.
Last Modified :
Oct. 22, 2026, 10:10 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | 83251b91-4cc7-4094-a5c7-464a1b83ea10 | ||||
| CVSS 3.1 | HIGH | [email protected] | ||||
| CVSS 3.1 | HIGH | MITRE-CVE | ||||
| CVSS 4.0 | MEDIUM | 83251b91-4cc7-4094-a5c7-464a1b83ea10 | ||||
| CVSS 4.0 | MEDIUM | [email protected] |
Solution
- Update SiYuan to version 3.7.4 or later.
- Apply vendor-provided security patches.
- Review and restrict access to sensitive endpoints.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-74905.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-74905 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-74905
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-74905 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-74905 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Translated by [email protected]
Oct. 22, 2026
Action Type Old Value New Value Added Translation Title: siyuan de siyuan-note, Description: SiYuan antes de la v3.7.4 contiene una vulnerabilidad de falsificación de petición del lado del servidor (SSRF) en la función isPrivateIP en kernel/util/net.go, utilizada por SSRFSafeDialer para aplicar la protección SSRF en SafeMode. La función solo verifica direcciones de bucle invertido, unicast de enlace local, privadas y no especificadas y no reconoce direcciones de transición IPv6 (NAT64 64:ff9b::/96, 6to4 2002::/16, Teredo 2001::/32) que incrustan destinos IPv4 privados. Cuando SafeMode está habilitado, un atacante autenticado puede eludir la protección SSRF a través de los puntos finales del proxy de reenvío de red, proxy WebSocket o proxy SSE al proporcionar una URL cuyo nombre de host se resuelve en una dirección de transición de este tipo, alcanzando servicios internos y puntos finales de metadatos en la nube (p. ej., 169.254.169.254). Debido a que el proxy de reenvío devuelve el cuerpo completo de la respuesta, esto es una SSRF de lectura completa que puede utilizarse para robar credenciales de instancia, alcanzar servicios internos y escanear puertos de la infraestructura interna. -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Aug. 19, 2026
Action Type Old Value New Value Added Reference https://github.com/siyuan-note/siyuan/security/advisories/GHSA-qq8m-8p8v-x4xg Added SSVC {'id': 'CVE-2026-74905', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'poc'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-08-19T14:09:42.098446Z'} -
New CVE Received by [email protected]
Aug. 18, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'siyuan-note', 'product': 'siyuan', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '3.7.4', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '3.7.4', 'versionType': 'semver'}], 'defaultStatus': 'unaffected'}] Added 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. Added CVSS V4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CVSS V3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N Added CWE CWE-918 Added Reference https://github.com/siyuan-note/siyuan/security/advisories/GHSA-qq8m-8p8v-x4xg Added Reference https://www.vulncheck.com/advisories/siyuan-before-ssrf-via-ipv6-transition-address-bypass