FXeSECVulnerability intelligence
CVE / 2026 / 19202

Token Cache Reuse in mcp-toolbox-sdk-python

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.

CVSS v4.0 9.1 · CRITICAL

CVE description

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 cached tokens by the requested audience. A valid, unexpired token minted for a sensitive service can consequently be retrieved from the cache and sent to a secondary service.

An attacker who operates, compromises, or monitors traffic to the secondary service can capture the token and replay it to impersonate the victim application against the sensitive service.

CVSS metrics

Version4.0
Score9.1 — Critical
VectorCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
Attack vectorNetwork
Attack complexityLow
Attack requirementsPresent: the attack depends on specific conditions, including a race condition or network injection.
Privileges requiredNone
User interactionNone
ImpactHigh confidentiality and integrity impact; no availability impact.

Related weakness

CWE-524 — Use of Cache Containing Sensitive Information. The cache contains sensitive information that may be read outside the intended control sphere.

Reference reviewed and summarized by FXeSEC.