CVE-2026-33203
Received Received - Intake
WebSocket Unauthenticated Access and DoS in SiYuan Kernel

Publication date: 2026-03-20

Last updated on: 2026-03-23

Assigner: GitHub, Inc.

Description
SiYuan is a personal knowledge management system. Prior to version 3.6.2, the SiYuan kernel WebSocket server accepts unauthenticated connections when a specific "auth keepalive" query parameter is present. After connection, incoming messages are parsed using unchecked type assertions on attacker-controlled JSON. A remote attacker can send malformed messages that trigger a runtime panic, potentially crashing the kernel process and causing denial of service. Version 3.6.2 fixes the issue.
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Meta Information
Published
2026-03-20
Last Modified
2026-03-23
Generated
2026-06-16
AI Q&A
2026-03-21
EPSS Evaluated
2026-06-15
NVD
CVE-2026-33203
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
b3log siyuan to 3.6.2 (exc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-248 An exception is thrown from a function, but it is not caught.
CWE-306 The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.
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Executive Summary

This vulnerability exists in the SiYuan personal knowledge management system prior to version 3.6.2. The kernel WebSocket server accepts unauthenticated connections if a specific "auth keepalive" query parameter is present. Once connected, the server parses incoming messages using unchecked type assertions on attacker-controlled JSON data. A remote attacker can exploit this by sending malformed messages that cause a runtime panic, potentially crashing the kernel process.

Impact Analysis

The primary impact of this vulnerability is a denial of service condition. An attacker can remotely crash the SiYuan kernel process by sending specially crafted malformed messages, causing the system to become unavailable or unstable.

Compliance Impact

I don't know

Detection Guidance

I don't know

Mitigation Strategies

To mitigate this vulnerability, you should upgrade SiYuan to version 3.6.2 or later, as this version fixes the issue where the kernel WebSocket server accepts unauthenticated connections and prevents denial of service caused by malformed messages.

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