Is CVE-2026-33203 in the CISA KEV catalog?

No. CVE-2026-33203 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-33203?

CVE-2026-33203 has a CVSS v3 base score of 7.5 (HIGH).

What is the EPSS score for CVE-2026-33203?

CVE-2026-33203 has an EPSS score of 0.50% (39th percentile), estimating the probability of exploitation in the next 30 days.

CVE & CISA-KEV Catalog

CVE-2026-33203

HIGH

7.5

CVSS v3

NVD

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.

CWE-248 CWE-306

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityNone

AvailabilityHigh

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

Exploit Intelligence

0.50%probability of exploitation in 30 days

39thpercentile

Low risk: more likely to be exploited than 39% of all known CVEs.

References

https://github.com/siyuan-note/siyuan/security/advisories/GHSA-3g9h-9hp4-654v

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-03-23.