CVE-2026-42889 (GCVE-0-2026-42889)
Vulnerability from cvelistv5 – Published: 2026-05-12 19:30 – Updated: 2026-05-13 12:32
VLAI
EPSS
VEX
Title
Relay Server WebSocket authentication bypass when token is omitted
Summary
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.
Severity
9.1 (Critical)
SSVC
Exploitation: poc
Automatable: yes
Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-05-13 12:32 UTC
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://github.com/No-Instructions/relay-server/s… | x_refsource_CONFIRM |
Impacted products
1 product
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| No-Instructions | relay-server |
Affected:
>= 0.9.0, < 0.9.7
|
guessed |
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Nomenclature
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The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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