Vulnerability · Published Oct 19, 2026 · Assigned by Google
CVE-2026-102503Missing Authentication on /libp2p-http Ingress in Google OSS Agent Mesh (SAM)
Critical 9.3
In plain English
A critical-severity missing authentication in SAM from Google. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 37% of all known vulnerabilities).
Official description
Missing Authentication for Critical Function (CWE-306) and Missing Authorization (CWE-862) in the /libp2p-http ingress server (StartIngressServer in cmd/sam-node/node.go) in Google OSS Agent Mesh (SAM) versions 0.1.0-alpha.1 through 0.1.0-alpha.2 allow an unauthenticated remote libp2p peer to bypass Biscuit capability policy enforcement and invoke arbitrary registered backend services (including command/stdio-backed MCP servers, A2A, and inference endpoints). While the MCP protocol stream handler enforces WithBiscuitAuth and Authorize checks, the parallel /libp2p-http ingress routes requests directly to backend service handlers without verifying a Biscuit token or mesh enrollment. Users should upgrade to version 0.1.0-alpha.3 or later.
Affected products (as reported)
Weakness: CWE-306, CWE-862 · 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
References
- https://github.com/google/sam/security/advisories/GHSA-r6hp-67wp-c7jx vendor-advisory
- https://github.com/google/sam/commit/433bc99d2a2c10071167bf22acc2c930a12e64e1 patch
- https://github.com/google/sam/releases/tag/v0.1.0-alpha.3 release-notes
- https://github.com/google/agentmesh/security/advisories/GHSA-r6hp-67wp-c7jx exploit