Reference page — cumulative record through Tuesday, October 20, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.
CVE-2026-103091
Google SAM — Insecure Default Policy and Unrestricted OIDC Enrollment in Google OSS Agent Mesh (SAM)
AV AC AT PR UI VC VI VA CVSS EPSS %ile KEV
N L N N N H H H 9.3 .0041 33.5 —
AFFECTED
Product Versions Fixed
SAM 0.1.0-alpha.1 – —
TIMELINE
Sep 30 Reserved by Google
Oct 19 EXPLOIT PUBLISHED — CVE-2026-103091 (Google SAM). Public exploit reference added.
Oct 19 Published (CNA: Google)
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.
Lifecycle
Complete event history — 3 events, chronological
| Date | Event | Detail |
|---|
| September 30, 2026 | Reserved | Reserved by Google |
| October 19, 2026 | EXPLOIT PUBLISHED | EXPLOIT PUBLISHED — CVE-2026-103091 (Google SAM). Public exploit reference added. |
| October 19, 2026 | Published | Published (CNA: Google) |
Affected
Affected products and packages — 1 row
| Vendor | Product / Package | Ecosystem | Version introduced | Fixed |
|---|
| Google | SAM | — | 0.1.0-alpha.1 | — |
About this page
This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2026-103091 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Tuesday, October 20, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.
