CVE-2026-33203 | SiYuan has an Unauthenticated WebSocket DoS via Auth Keepalive Bypass

Exp

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.

Published: 2026-03-20 Last update: 2026-03-23 Assigner: [email protected] Source: [email protected]

Conclusion & alert: CVE-2026-33203 is rated Exploit Available (52.1/100): CVSS High severity, with low exploitation likelihood (EPSS 0.07%). Core evidence: 1 public exploit reference(s) are indexed (Exploit-DB). Mandatory action: Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2026-33203

EDB-ID Source Kind Published Link
nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2026-33203

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-01 0.05% 0.07% +0.02%
2 2026-04-21 0.10% 0.05% -0.05%
3 2026-03-21 0.10%

Full EPSS history (3 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-33203

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
3.9 3.6 [email protected]

Weakness enumeration for CVE-2026-33203

GitHub Security Advisory for CVE-2026-33203

GHSA-3g9h-9hp4-654v · Severity: high · Ecosystem: go — SiYuan has an Unauthenticated WebSocket DoS via Auth Keepalive Bypass

Affected software / configurations for CVE-2026-33203

Vendor Product Version Raw CPE
b3log siyuan < 3.6.2 cpe:2.3:a:b3log:siyuan:*:*:*:*:*:*:*:*

References for CVE-2026-33203

cvelogic Threat Intelligence