CVE-2026-102503 Missing Authentication on /libp2p-http Ingress in Google OSS Agent Mesh (SAM)
Unauthenticated remote peers can bypass security policies to invoke arbitrary backend services, including command execution, in Google SAM.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-102503?
CVE-2026-102503 is a critical missing authorization vulnerability in Google SAM, published on 19 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
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.
Which versions are affected by CVE-2026-102503?
How do I fix CVE-2026-102503?
No fix has been published for CVE-2026-102503 yet. Limit exposure of the affected software until one is available.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-102503 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-102503 exists.
Sources
Also known as GHSA-r6hp-67wp-c7jx, GHSA-vc9x-qg3j-cxg6.