CVE-2026-42889

Status: DeferredCritical (9.1)—

Relay adds real-time collaboration to Obsidian. Relay Server versions 0.9.0 through 0.9.6 contain an authentication bypass in the multi-document WebSocket endpoints. When authentication is configured, WebSocket connections without a token query parameter were incorrectly treated as having full server permissions. An unauthenticated network attacker who knows or guesses a document ID could connect to the document sync WebSocket and read or modify document contents without a valid document token. This vulnerability is fixed in 0.9.7.

CVSS

Version: 3.1
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Base score: 9.1

Exploitation probability (EPSS)

Probability of exploitation in the next 30 days: 0.53%
Percentile among all scored CVEs: 43
Score date: 10/5/2026

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

🎯 ATT&CK techniques

How this vulnerability is exploited and what the attacker gains, in MITRE ATT&CK terms.

ExploitationT1190 Exploit Public-Facing Applicationinitial access85 %
Primary impactT1078 Valid Accountsstealth · persistence · privilege escalation · initial access80 %
Secondary impactT1005 Data from Local Systemcollection85 %

AV:N/PR:N/UI:N indica vulnerabilidad remota sin autenticación. Bypass de autenticación en WebSocket (CWE-863) permite leer/modificar documentos sin token válido: acceso no autorizado (T1078) y lectura de datos (T1005).

Inferred by our analysis agent from the official description, CVSS vector and CWE, and checked by a supervisor. May contain errors.

🛡️ ATT&CK mitigations that cover these techniques

Privileged Account Management Application Developer Guidance Active Directory Configuration Vulnerability Scanning User Training User Account Management

Affected technologies (2)

⚠ AI-inferred from the description — NVD hasn't analyzed this CVE yet, these aren't verified CPEs.

Obsidian — Obsidian^AI Relay — Relay Server^AI

CWEs

CWE-639, CWE-863

References

Raw JSON (NVD)

Show

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  "published": "2026-05-12T20:16:42.143",
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  "lastModified": "2026-06-17T10:48:34.350",
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