CVE-2026-82234: SiYuan before v3.8.1 SSRF via DNS-Rebinding TOCTOU

Severity: high (CVSS 8.2 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-08-28 · updated 2026-08-28
Weakness: CWE-918

Description

SiYuan versions before v3.8.1 contain a server-side request forgery vulnerability in the http_request and web_fetch agent tools that perform DNS resolution only at guard time without validating the connect-time resolution. Attackers can use DNS rebinding to answer the guard resolution with a public IP and the connect resolution with a private or metadata IP, bypassing the SSRF defense to access cloud instance metadata and internal services.

Affected products

Go Github.Com/Siyuan-Note/Siyuan/Kernel: before 0.0.0-20260813142806-dd2778b70d02 — fixed in 0.0.0-20260813142806-dd2778b70d02
siyuan-note siyuan: before 3.8.1 — fixed in 3.8.1

How to fix

Upgrade to a fixed version: Go Github.Com/Siyuan-Note/Siyuan/Kernel 0.0.0-20260813142806-dd2778b70d02; siyuan-note siyuan 3.8.1. Check the vendor advisory for mitigations.

References

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