Vulnerability · Published Dec 2, 2025 · Assigned by GitHub_M
CVE-2025-66454Arcade MCP Default Hardcoded Worker Secret Allows Full Unauthorized Access to All HTTP MCP Worker Endpoints
Medium 6.5
In plain English
A medium-severity hard-coded credentials in arcade-mcp from ArcadeAI. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 27% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| PyPI | arcade-mcp-server | 1.9.1 | GHSA-g2jx-37x6-6438 |
| PyPI | arcade-mcp-server | 1.9.1 | PYSEC-2026-1192 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| ArcadeAI | arcade-mcp | < 1.5.4 |
Weakness: CWE-321, CWE-798 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
References
- https://github.com/ArcadeAI/arcade-mcp/security/advisories/GHSA-g2jx-37x6-6438 x_refsource_CONFIRM
- https://github.com/ArcadeAI/arcade-mcp/pull/691 x_refsource_MISC
- https://github.com/ArcadeAI/arcade-mcp/commit/44660d18ceb220600401303df860a31ca766c817 x_refsource_MISC