CVE-2026-103091 (GCVE-0-2026-103091)
Vulnerability from cvelistv5 – Published: 2026-10-19 02:24 – Updated: 2026-10-19 17:44
VLAI
EPSS
VEX
Title
Insecure Default Policy and Unrestricted OIDC Enrollment in Google OSS Agent Mesh (SAM)
Summary
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.
Severity
SSVC
Exploitation: poc
Automatable: no
Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-10-19 17:43 UTC
CWE
Assigner
References
3 references
| URL | Tags |
|---|---|
| https://github.com/google/sam/security/advisories… | vendor-advisory |
| https://github.com/google/sam/releases/tag/v0.1.0… | release-notes |
| https://github.com/google/agentmesh/security/advi… | exploit |
Impacted products
Date Public
2026-09-06 16:01
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