CVE-2026-19202: Token Cache Reuse in mcp-toolbox-sdk-python
- Is it exploited?
Not on CISA's list. CISA has not added it to the Known Exploited Vulnerabilities catalog as of . If CISA adds it, this page shows it as known exploited.
- How likely is exploitation in the next 30 days?
- 0.2%
Down from 0.3% on .
EPSS score, percentile 13.6 of all scored records. A probability estimated by FIRST, not a report of exploitation.
- How severe?
- 9.1 Critical
CVSS v4.0 base score, given by the CNA
- What should I do?
CISA has set no required action, because the vulnerability is not in KEV.
- Which versions are affected?
Affected
- 1.1.0 and earlier
Source: CISA KEV 2026.10.29, as of ; FIRST EPSS, as of ; CVE List, as of . About the data.
What to do
Advisories and patches
This summary is based on the CVE record as of . Check the vendor's advisory before you act: affected versions and fixes can change.
Affected products and versions
As listed in the CVE record.
| Status | Versions |
|---|---|
| Affected | 1.1.0 and earlier |
Versions not listed are: unaffected.
Source: CVE List, as of . About the data.
About this vulnerability
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 minte…
Summary: CVE record, as of .
- CISA has not added CVE-2026-19202 to its Known Exploited Vulnerabilities (KEV) catalog, as of 29 Oct 2026.
- The CVE record was published on 22 Sep 2026.
- The CVE record carries a CVSS v4.0 base score of 9.1 (Critical), given by its CNA.
- FIRST's EPSS model puts the probability of exploitation in the next 30 days at 0.2% (percentile 13.6), as of 29 Oct 2026. EPSS is a statistical estimate, not a report of exploitation.
- CISA's SSVC assessment in the CVE record: exploitation none, automatable yes, technical impact total.
Source: CISA KEV 2026.10.29, as of ; CVE List, as of ; FIRST EPSS, as of . About the data.
Description
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. 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.
Source: CVE List, as of . About the data.
Weakness
CWE-524, 1 CAPEC
- CWE-524: Use of a Shared Cache with Insufficient Key Granularity
Attack patterns (CAPEC)
- CAPEC-60: Reusing Session IDs (Spoofing)
CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record.
Timeline
| Date | Event |
|---|---|
| CVE record published | |
| CVE record last updated |
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