CVE Catalog

CVE-2026-108586

MediumCVSS 5.4
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.19%

8th percentile - higher than 8% of all known CVEs

Summary

1MCP Agent (@1mcp/agent) versions 0.20.0 through 0.39.0 contain an incorrect authorization vulnerability that allows authenticated clients to bypass OAuth tag-scope enforcement using negated advanced tag-filter expressions. Attackers holding a single-tag token can send a filter like not <granted-tag> to list and invoke tools on backend MCP servers outside their granted scopes.

Risk Assessment

The risk includes unauthorized access to tools and data on MCP servers, potentially leading to confidentiality and integrity breaches and unauthorized actions in the system.

Recommendation

Update @1mcp/agent to a patched version and review and strengthen authorization logic to prevent tag-scope bypass. Also, audit permissions and monitor suspicious queries.

Related vulnerabilities

Original NVD description (English source)

1MCP Agent (@1mcp/agent) 0.20.0 through 0.39.0 contains an incorrect authorization vulnerability that allows authenticated clients to bypass OAuth tag-scope enforcement using negated advanced tag-filter expressions. Attackers holding a single-tag token can send a filter like not <granted-tag> to list and invoke tools on backend MCP servers outside their granted scopes.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS