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01 Record

CVE-2026-11717

An authentication bypass vulnerability exists in the generic opaque token validation path (validateOpaqueToken) of googleapis/mcp-toolbox. When verifying an unparsed opaque token via an OAuth 2.0

CriticalPUBLISHEDCNA: Google
CNA base score9.3 CVSS v4.0CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

02 Description

An authentication bypass vulnerability exists in the generic opaque token validation path (validateOpaqueToken) of googleapis/mcp-toolbox. When verifying an unparsed opaque token via an OAuth 2.0

03 Exploitation and scoring

Exploitation
Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.
SSVC decision
  • ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
  • AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
  • Technical ImpacttotalSuccessful exploitation gives total control of the vulnerable component.
CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.
EPSS probability
0.17% probability of exploitation activity in the next 30 days.
EPSS percentile
Equal to or higher than the score of 7.1% of scored records. A rank, not a probability.
NVD base score
9.3 (CVSS v4.0), scored by the NVD independently of the CNA.
NVD CVSS vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD analysis status
Analyzed. NVD last modified this record on 2026-10-26.
Red Hat severity
No Red Hat rating. Red Hat rates the CVEs that affect its products.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

04 Metadata

Published
2026-06-18 11:50Z4 MO AGO
Last updated
2026-06-18 12:23Z4 MO AGO
Reserved
2026-06-09
Assigning CNA
Google
Record state
PUBLISHED
Severity
Critical (CVSS 9.3)
CNA CVSS vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
Weaknesses
  • CWE-287Improper AuthenticationClass
Data version
5.2
Document digest
9decec7262674c1cc3a48b370b3132caa1696bb6100d4b257159f6610efcb227

05 Affected products

VendorProductVersionsPlatforms

06 References