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.
History

Wed, 23 Sep 2026 16:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Wed, 23 Sep 2026 12:30:00 +0000

Type Values Removed Values Added
First Time appeared Google
Google mcp-toolbox-sdk-python
Vendors & Products Google
Google mcp-toolbox-sdk-python

Tue, 22 Sep 2026 22:00:00 +0000

Type Values Removed Values Added
Description 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.
Title Token Cache Reuse in mcp-toolbox-sdk-python
Weaknesses CWE-524
References
Metrics cvssV4_0

{'score': 9.1, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: Google

Published: 2026-09-22T21:48:26.539Z

Updated: 2026-09-23T15:01:51.542Z

Reserved: 2026-08-07T05:27:47.674Z

Link: CVE-2026-19202

cve-icon Vulnrichment

Updated: 2026-09-23T15:01:48.646Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-09-22T22:17:11.707

Modified: 2026-09-23T19:42:48.540

Link: CVE-2026-19202

cve-icon Redhat

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