CVE Catalog

CVE-2026-19202

CriticalCVSS 9.1
Published: Translated: NVD NIST

Summary

A caching flaw in the toolbox-core package of the mcp-toolbox-sdk-python SDK causes the same Google ID token to be cached and reused across different audiences. If an application uses the SDK to authenticate to two or more different audiences within the same process, the module-level token cache fails to key its cached tokens by the requested audience. Consequently, a valid, unexpired token minted for a sensitive service (Service A) can be retrieved from the cache and sent to a secondary service (Service B). An attacker who operates, compromises, or monitors traffic to Service B can capture this token and replay it to impersonate the victim application against Service A.

Risk Assessment

The ability to impersonate the application against sensitive services could lead to unauthorized access to data or operations in those services.

Recommendation

Update the SDK to a version where token cache keying by audience is fixed, and consider using separate processes for different audiences.

Related vulnerabilities

Original NVD description (English source)

A caching flaw in the toolbox-core package of the mcp-toolbox-sdk-python SDK causes the same Google ID token to be cached and reused across different audiences. If an application uses the SDK to authenticate to two or more different audiences within the same process, the module-level token cache fails to key its cached tokens by the requested audience. Consequently, a valid, unexpired token minted for a sensitive service (Service A) can be retrieved from the cache and sent to a secondary service (Service B). An attacker who operates, compromises, or monitors traffic to Service B can capture this token and replay it to impersonate the victim application against Service A.

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