CVE-2026-82234
Received Received - Intake

SiYuan SSRF via DNS Rebinding in Agent Tools

Publication date: 2026-08-28

Last updated on: 2026-08-28

Assigner: VulnCheck

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.

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Meta Information

Published
2026-08-28
Last Modified
2026-08-28
Generated
2026-08-28
AI Q&A
2026-08-28
EPSS Evaluated
N/A
NVD
CVE-2026-82234
EUVD
EUVD-2026-67686

Affected Vendors & Products

Currently, no data is known.

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Exploitability

CWE
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KEV
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CWE ID Description
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.

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Executive Summary

SiYuan versions before v3.8.1 have a server-side request forgery (SSRF) vulnerability in the http_request and web_fetch agent tools. These tools perform DNS resolution only during a guard check without validating the resolution at connection time. Attackers can exploit this by using DNS rebinding to trick the system into resolving a public IP during the guard check and a private or metadata IP during the actual connection, bypassing SSRF defenses to access cloud instance metadata and internal services.

Impact Analysis

This vulnerability allows attackers to access internal services and cloud instance metadata that should be protected. If exploited, it could lead to unauthorized data exposure, service disruption, or further attacks on internal systems. Users running vulnerable SiYuan versions risk data breaches or unauthorized access to sensitive information.

Compliance Impact

This vulnerability could lead to non-compliance with GDPR, HIPAA, and other regulations by enabling unauthorized access to sensitive data. GDPR requires protecting personal data, while HIPAA mandates safeguarding health information. Exploitation may result in data breaches, triggering legal penalties, fines, or reputational damage for organizations.

Mitigation Strategies

Upgrade SiYuan to version v3.8.1 or later to address the SSRF vulnerability in http_request and web_fetch tools.

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