Insecure Default Policy and Unrestricted OIDC Enrollment in Google OSS Agent Mesh (SAM)
- Published
- Last modified
- Status
- published
- Known exploitation
- Not listed in CISA KEV
- Fix
- Fixed in 0.1.0-alpha.9
- Public exploit
- None on Exploit-DB
- Exploitation: poc
- Automatable: no
- Technical impact: total
?
Decision points from CISA's Vulnrichment, assessed (SSVC 2.0.3).
SSVC documentationSummary
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.
Affected versions
- github.com/google/sam
From 0.1.0-alpha.1 · fixed in 0.1.0-alpha.9