Description
Missing Authorization (CWE-862) and Initialization of a Resource with an Insecure Default (CWE-1188) in the MCP proxy (HandleStreamPassThrough in mcp_service.go) and OIDC registration flow (GET /info and POST /register in internal/controlplane/server.go) in Google OSS Agent Mesh (SAM) versions 0.1.0-alpha.1 through 0.1.0-alpha.8 allow a remote attacker to self-enroll into the mesh and invoke arbitrary tools across all connected MCP backend nodes. Because GET /info publicly discloses OIDC configuration, POST /register auto-enrolls any valid OIDC token holder without claim filtering or ban checks, and the default policy binds sam:system:authenticated to wildcard services and targets, an attacker can obtain a mesh credential with full read, write, and execution access on backend services. Users should upgrade to version 0.1.0-alpha.9 or later, which enforces a fail-closed default policy, explicit policy-binding requirements on enrollment, and ban checks.
Published: 2026-10-19
Score: 9.3 Critical
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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History

Mon, 19 Oct 2026 18:30:00 +0000

Type Values Removed Values Added
References
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Mon, 19 Oct 2026 02:45:00 +0000

Type Values Removed Values Added
Description Missing Authorization (CWE-862) and Initialization of a Resource with an Insecure Default (CWE-1188) in the MCP proxy (HandleStreamPassThrough in mcp_service.go) and OIDC registration flow (GET /info and POST /register in internal/controlplane/server.go) in Google OSS Agent Mesh (SAM) versions 0.1.0-alpha.1 through 0.1.0-alpha.8 allow a remote attacker to self-enroll into the mesh and invoke arbitrary tools across all connected MCP backend nodes. Because GET /info publicly discloses OIDC configuration, POST /register auto-enrolls any valid OIDC token holder without claim filtering or ban checks, and the default policy binds sam:system:authenticated to wildcard services and targets, an attacker can obtain a mesh credential with full read, write, and execution access on backend services. Users should upgrade to version 0.1.0-alpha.9 or later, which enforces a fail-closed default policy, explicit policy-binding requirements on enrollment, and ban checks.
Title Insecure Default Policy and Unrestricted OIDC Enrollment in Google OSS Agent Mesh (SAM)
Weaknesses CWE-1188
CWE-200
CWE-306
CWE-862
CWE-863
References
Metrics cvssV4_0

{'score': 9.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N'}


Subscriptions

No data.

cve-icon MITRE

Status: PUBLISHED

Assigner: Google

Published:

Updated: 2026-10-19T17:44:31.625Z

Reserved: 2026-09-30T01:36:24.048Z

Link: CVE-2026-103091

cve-icon Vulnrichment

Updated: 2026-10-19T17:44:17.843Z

cve-icon NVD

Status : Received

Published: 2026-10-19T03:16:58.377

Modified: 2026-10-19T18:16:58.770

Link: CVE-2026-103091

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-19T03:30:06Z

Weaknesses
  • CWE-1188

    Initialization of a Resource with an Insecure Default

  • CWE-200

    Exposure of Sensitive Information to an Unauthorized Actor

  • CWE-306

    Missing Authentication for Critical Function

  • CWE-862

    Missing Authorization

  • CWE-863

    Incorrect Authorization