CVE-2026-33203Public exploitNetwork attack vector

Kernel crash via unauthenticated WebSocket type assertions

Published Mar 20, 2026 · Updated Mar 20, 2026

Denial of service in the SiYuan kernel before 3.6.2 allows remote attackers to crash the process through an unauthenticated WebSocket. The handler in kernel/server/serve.go accepts an authentication-keepalive query pattern without credentials, then asserts attacker-controlled JSON fields as fixed Go types without validation or panic recovery. Network access to the kernel HTTP service is sufficient; malformed JSON causes a runtime panic, and repeated requests can keep the service unavailable.

CVSS severity7.5
High
EPSS probability0.50%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in the SiYuan kernel before 3.6.2 allows remote attackers to crash the process through an unauthenticated WebSocket. The handler in kernel/server/serve.go accepts an authentication-keepalive query pattern without credentials, then asserts attacker-controlled JSON fields as fixed Go types without validation or panic recovery. Network access to the kernel HTTP service is sufficient; malformed JSON causes a runtime panic, and repeated requests can keep the service unavailable.

The record

CVE
CVE-2026-33203
Published
Mar 20, 2026
Updated
Mar 20, 2026
Vendor
SiYuan Note
Product
SiYuan
Classifications
CWE-20, CWE-306, CWE-248, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 20, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 3.6.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

SiYuan Note · SiYuanversion=< 3.6.2

Published CVSS scores

7.5GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-20Improper Input Validation
CWE-306Missing Authentication for Critical Function
CWE-248Uncaught Exception
T1499Endpoint Denial of Service

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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