CVE-2026-42889 PUBLISHED

Relay Server WebSocket authentication bypass when token is omitted

Assigner: GitHub_M
Reserved: 30.04.2026 Published: 12.05.2026 Updated: 12.05.2026

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.

Metrics

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

Product Status

Vendor No-Instructions
Product relay-server
Versions
  • Version >= 0.9.0, < 0.9.7 is affected

References

Problem Types

  • CWE-863: Incorrect Authorization CWE
  • CWE-639: Authorization Bypass Through User-Controlled Key CWE