CVE-2026-42889

CRITICAL

Relay Server WebSocket authentication bypass when token is omitted

Title source: cna
STIX 2.1

Description

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.

References (1)

Core 1
Core References

Scores

CVSS v3 9.1
EPSS 0.0037
EPSS Percentile 28.2%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

CISA SSVC

Vulnrichment
Exploitation poc
Automatable yes
Technical Impact total

Details

CWE
CWE-639 CWE-863
Status published
Products (1)
No-Instructions/relay-server >= 0.9.0, < 0.9.7
Published May 12, 2026
Tracked Since May 13, 2026