CVE-2025-66454Public exploitNetwork attack vector

Unauthenticated worker access via hardcoded JWT secret

Published Dec 2, 2025 · Updated Dec 2, 2025

Authentication bypass in Arcade AI arcade-mcp before 1.5.4 allows remote attackers to invoke MCP worker tools using forged JWTs. ArcadeSettings supplies the constant worker secret "dev" to FastAPIWorker, whose middleware accepts any HS256 JWT signed with that publicly known key. An HTTP deployment using the default secret exposes tool enumeration, tool invocation, returned data, and actions available through configured tools.

CVSS severity6.5
Medium
EPSS probability0.31%
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 Arcade AI arcade-mcp before 1.5.4 allows remote attackers to invoke MCP worker tools using forged JWTs. ArcadeSettings supplies the constant worker secret "dev" to FastAPIWorker, whose middleware accepts any HS256 JWT signed with that publicly known key. An HTTP deployment using the default secret exposes tool enumeration, tool invocation, returned data, and actions available through configured tools.

The record

CVE
CVE-2025-66454
Published
Dec 2, 2025
Updated
Dec 2, 2025
Vendor
Arcade AI
Product
arcade-mcp
Classifications
CWE-798, CWE-321, T1606
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 2, 2025CVE publishedPublication date reported by the CVE source.
  2. Dec 2, 2025Record 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=< 1.5.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Arcade AI · arcade-mcpversion=< 1.5.4

Published CVSS scores

6.5GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/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.

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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-798Use of Hard-coded Credentials
CWE-321Use of Hard-coded Cryptographic Key
T1606Forge Web Credentials

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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