CVE-2026-42889Public exploitNetwork attack vector

Unauthenticated document access via omitted WebSocket token

Published May 12, 2026 · Updated May 12, 2026

Authentication bypass in No Instructions LLC Relay Server 0.9.0 through 0.9.6 allows remote attackers to read or modify documents. In crates/relay/src/server.rs, both multi-document upgrade handlers mapped an absent token to server permission and then full authorization instead of rejecting the request. Authentication must be configured and remote attackers must know or guess a document ID; no valid document token or user interaction is required.

CVSS severity9.1
Critical
EPSS probability0.37%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in No Instructions LLC Relay Server 0.9.0 through 0.9.6 allows remote attackers to read or modify documents. In crates/relay/src/server.rs, both multi-document upgrade handlers mapped an absent token to server permission and then full authorization instead of rejecting the request. Authentication must be configured and remote attackers must know or guess a document ID; no valid document token or user interaction is required.

The record

CVE
CVE-2026-42889
Published
May 12, 2026
Updated
May 12, 2026
Vendor
No Instructions LLC
Product
Relay Server
Classifications
CWE-639, CWE-863, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 12, 2026CVE publishedPublication date reported by the CVE source.
  2. May 12, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 0.9.0, < 0.9.7

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

No Instructions LLC · Relay Serverversion=>= 0.9.0, < 0.9.7

Published CVSS scores

9.1GitHub CNACVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-639Authorization Bypass Through User-Controlled Key
CWE-863Incorrect Authorization
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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