Summary
atomic-agents-stack: HTTP MCP catalog accepts cleartext http and spawns catalog-supplied commands (MITM to RCE)
The HTTP MCP server-registry backend factory (atomic_agents/mcp_registry/http.py, make_http_mcp_server_registry_backend_from_url) accepts both http and https schemes. Catalog entries carry command/args that are type-validated but content-unrestricted, and are later spawned as local stdio subprocesses by MCPClientPool. Over a cleartext http:// catalog URL, a network man-in-the-middle can rewrite the catalog response to inject an arbitrary command/args and obtain code execution on the agent host, with no LLM involvement. The Policy MCP allowlist is not a default mitigation (mcp_allow_fn defaults to None), so absent an operator-authored allowlist every resolved spec connects.
Affected: mcp_registry/http.py, all versions through 1.0.0. (The https path is sound: httpx defaults to verify=True, follow_redirects=False.)
Fix: require https by default and gate http:// behind a loud explicit opt-in. Defense-in-depth: allowlist the resolved command basename (or require confirmation) before any registry-sourced subprocess spawn. Document the consequence in spec/36.
Impact
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
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Frequently Asked Questions
- What is GHSA-XHCR-CQFR-M3HV? GHSA-XHCR-CQFR-M3HV is a high-severity security vulnerability in atomic-agents-stack (pip), affecting versions <= 1.0.0. It is fixed in 1.1.0.
- Which versions of atomic-agents-stack are affected by GHSA-XHCR-CQFR-M3HV? atomic-agents-stack (pip) versions <= 1.0.0 is affected.
- Is there a fix for GHSA-XHCR-CQFR-M3HV? Yes. GHSA-XHCR-CQFR-M3HV is fixed in 1.1.0. Upgrade to this version or later.
- Is GHSA-XHCR-CQFR-M3HV exploitable, and should I be worried? Whether GHSA-XHCR-CQFR-M3HV is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether GHSA-XHCR-CQFR-M3HV is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix GHSA-XHCR-CQFR-M3HV? Upgrade
atomic-agents-stackto 1.1.0 or later.