CVE-2026-33203
HIGHCVE-2026-33203 is a high-severity (CVSS 7.5) CWE-248 vulnerability in github.com/siyuan-note/siyuan/kernel. O3 Security confirms whether CVE-2026-33203 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
SiYuan has an Unauthenticated WebSocket DoS via Auth Keepalive Bypass
Blast Radius
github.com/siyuan-note/siyuan/kernelReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/siyuan-note/siyuan/kernel | all versions | 3.6.2 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/siyuan-note/siyuan/kernel. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update github.com/siyuan-note/siyuan/kernel to 3.6.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-33203 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-33203 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-33203. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-33203 in your dependencies?
O3 detects CVE-2026-33203 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.