CVE-2025-66454

Arcade MCP Default Hardcoded Worker Secret Allows Full Unauthorized Access to All HTTP MCP Worker Endpoints

CVSS 6.5 MEDIUMEPSS 0.3%CWE-321 CWE-798

Vexday Risk Score

13Low

SSVC decision (CISA)

Track

No exploitation signal → monitor

CVSS 6.5EPSS 0.3%KEV nãoPoC —Nuclei —Metasploit —Patch —

Lifecycle

02 Dec 2025Published on NVD

Recommendation: Monitor — no exploitation signal at the moment.

Arcade MCP allows you to to create, deploy, and share MCP Servers. Prior to 1.5.4, the arcade-mcp HTTP server uses a hardcoded default worker secret ("dev") that is never validated or overridden during normal server startup. As a result, any unauthenticated attacker who knows this default key can forge valid JWTs and fully bypass the FastAPI authentication layer. This grants remote access to all worker endpoints—including tool enumeration and tool invocation—without credentials. This vulnerability is fixed in 1.5.4.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

Affected products

ArcadeAI · arcade-mcp

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References

https://github.com/ArcadeAI/arcade-mcp/commit/44660d18ceb220600401303df860a31ca766c817 https://github.com/ArcadeAI/arcade-mcp/pull/691 https://github.com/ArcadeAI/arcade-mcp/security/advisories/GHSA-g2jx-37x6-6438