Medium 6.5Published Dec 2, 2025

CVE-2025-66454Arcade MCP Default Hardcoded Worker Secret Allows Full Unauthorized Access to All HTTP MCP Worker Endpoints

Updated under an hour ago (Oct 28, 2026, 8:20 AM ET)

Does this affect you?

It affects ArcadeAI arcade-mcp. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

Do this next

Start free and add your stack

Free account, 1 product

Every CVE for ArcadeAI arcade-mcp

Exploited in the last 30 days

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: 6.5 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Weakness (CWE): CWE-321, CWE-798
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Deferred
Record last updated: Dec 2, 2025
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

ArcadeAI arcade-mcp arcadeai:arcade_mcp (from the name)	before 1.5.4	CNA record

References

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

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.