CVE-2026-19202
CVE-2026-19202 is a critical-severity vulnerability with a CVSS 4.0 base score of 9.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-524.
Key facts
- Severity: Critical (CVSS 4.0 base score 9.1)
- EPSS exploit prediction: 0% (15th percentile)
- Actively exploited: Not listed in CISA KEV
- Weakness: CWE-524
- Published:
- Last modified:
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.
Frequently asked questions
- What is CVE-2026-19202?
- 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.
- How severe is CVE-2026-19202?
- CVE-2026-19202 has a CVSS 4.0 base score of 9.1, rated critical severity.
- Is CVE-2026-19202 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (15th percentile), an estimate of the probability of exploitation in the next 30 days.
- How do I fix CVE-2026-19202?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
- When was CVE-2026-19202 published?
- CVE-2026-19202 was published on 2026-09-22 and last updated on 2026-09-23.
References
Other CWE-524 vulnerabilities
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