# 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.

- **Severity:** Critical 9.3 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 19 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** GHSA-r6hp-67wp-c7jx, GHSA-vc9x-qg3j-cxg6

## 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.

Weakness: CWE-862 (Missing Authorization), CWE-306 (Missing Authentication for Critical Functionality)

## 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.

## Is CVE-2026-102503 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-102503 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-102503 and fix it if it is affected.

What it is: 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.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-102503 exists.

Affected product: Google SAM. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-102503/ (Markdown: https://insights.sbomify.com/CVE-2026-102503/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-102503
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-102503
- OSV: https://osv.dev/vulnerability/CVE-2026-102503

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-102503/
Summaries are generated and may contain mistakes; the official description above is the record.