{"id":"CVE-2026-103091","revision":"3b1b8fc447bf4e71bf67c51493c114e9","records":[{"revision":"3b1b8fc447bf4e71bf67c51493c114e9","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-103091","aliases":[],"title":"Insecure Default Policy and Unrestricted OIDC Enrollment in Google OSS Agent Mesh (SAM)","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.","state":0,"publishedAt":"2026-10-19T02:24:35.225+00:00","modifiedAt":"2026-10-19T17:44:31.625+00:00","affected":[{"ecosystem":"Vendor product","name":"github.com/google/sam","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"Google\",\n                    \"product\": \"SAM\",\n                    \"packageName\": \"github.com/google/sam\",\n                    \"versions\": [\n                        {\n                            \"status\": \"affected\",\n                            \"version\": \"0.1.0-alpha.1\",\n                            \"lessThan\": \"0.1.0-alpha.9\",\n                            \"versionType\": \"semver\"\n                        }\n                    ],\n                    \"defaultStatus\": \"unaffected\"\n                }"}],"metrics":[{"system":"CVSS 4.0","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","score":9.3,"severity":"CRITICAL"}],"references":["https://github.com/google/sam/security/advisories/GHSA-cgmg-9xf6-rrgw","https://github.com/google/sam/releases/tag/v0.1.0-alpha.9"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-103091","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-103091","identifiers":["CVE-2026-103091"]},"retained":false,"historicalAffected":[]}],"coverage":[]}