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.
CVE-2025-66454
This medium-severity CVE scores 6.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3%, top 79% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
- Lower severity and no public exploit yet
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 6.5
- EG Score
- 6.5(medium)
- EG Risk
- 45(Track)EG Risk 45/100SSVC: Track
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computedSeverity65% × 45%Exploitation40% × 40%Automatability0% × 15%Action: Routine — remediate on your standard cadence. - EPSS
- 20.9%
- KEV
- Not listed
Published
December 2, 2025
Last Modified
June 17, 2026
References (3)
- security-advisories@githubhttps://github.com/ArcadeAI/arcade-mcp/commit/44660d18ceb220600401303df860a31ca766c817
- security-advisories@githubhttps://github.com/ArcadeAI/arcade-mcp/pull/691
- security-advisories@githubhttps://github.com/ArcadeAI/arcade-mcp/security/advisories/GHSA-g2jx-37x6-6438
Affected Packages
(1 across 1 ecosystem)
PyPI(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| arcade-mcp-server | 1.0.0 ... 1.8.0 (22 versions) | 1.9.1 | — |
Weakness Classification(2)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 12× in last 7d / 47× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
Showing the most recent 100 of 113 total refreshes for this CVE.
- 2026-07-23 14:18 UTCEPSS rescore
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Related CVEs(same CWE)
Same CWE
10 shownCWE-798 · CWE-321
Frequently asked(5)
What is CVE-2025-66454?
When was CVE-2025-66454 disclosed?
Is CVE-2025-66454 actively exploited?
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Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2025-66454
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