SiYuan has an Unauthenticated WebSocket DoS via Auth Keepalive Bypass

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-33203: 0.52% estimated exploitation activity in the next 30 days; percentile 44.03 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary 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. Details 1. Authentication Bypass via Keepalive Query Unauthenticated connections are accepted if the request URI matches a specific pattern intended for an authentication page keepalive. File: kernel/server/serve.go 2. Unsafe Type Assertions on Untrusted Input Incoming JSON messages are parsed into a generic map and fields are accessed without validation. File: kernel/server/serve.go Malformed or missing fields trigger a runtime panic. The handler does not implement local panic recovery, allowing crashes to propagate. PoC Step 1 — Prepare workspace directory Step 2 — Run SiYuan container Service…

Published by the source

18 Mar 2026, 20:11 UTC

Last modified by the source

25 Mar 2026, 18:12 UTC

Source last checked

26 Oct 2026, 15:18 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-3g9h-9hp4-654v

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# Patch Next advisory brief: CVE-2026-33203

Advisory: SiYuan has an Unauthenticated WebSocket DoS via Auth Keepalive Bypass
IDs: CVE-2026-33203, GHSA-3g9h-9hp4-654v
Record: https://patchnext.com/advisories/cve-2026-33203 (revision 1, source checked 26 Oct 2026, 15:18 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/siyuan-note/siyuan/kernel 3.6.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/siyuan-note/siyuan/kernel: affected <= 3.6.1; fixed in 3.6.2

## Suggested inspection (read-only)
- Go github.com/siyuan-note/siyuan/kernel: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/siyuan-note/siyuan/kernel.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-3g9h-9hp4-654v (GitHub-reviewed advisory GHSA-3g9h-9hp4-654v lists affected ranges: Go github.com/siyuan-note/siyuan/kernel >=0 <=3.6.1)

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