GHSA-XHCR-CQFR-M3HV
Vulnerability from github – Published: 2026-08-17 21:49 – Updated: 2026-08-17 21:49The 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.
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 1.0.0"
},
"package": {
"ecosystem": "PyPI",
"name": "atomic-agents-stack"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "1.1.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [],
"database_specific": {
"cwe_ids": [
"CWE-319",
"CWE-494"
],
"github_reviewed": true,
"github_reviewed_at": "2026-08-17T21:49:55Z",
"nvd_published_at": null,
"severity": "HIGH"
},
"details": "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.\n\n**Affected:** `mcp_registry/http.py`, all versions through 1.0.0. (The `https` path is sound: `httpx` defaults to `verify=True`, `follow_redirects=False`.)\n\n**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.",
"id": "GHSA-xhcr-cqfr-m3hv",
"modified": "2026-08-17T21:49:55Z",
"published": "2026-08-17T21:49:55Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/dep0we/atomic-agents-stack/security/advisories/GHSA-xhcr-cqfr-m3hv"
},
{
"type": "PACKAGE",
"url": "https://github.com/dep0we/atomic-agents-stack"
},
{
"type": "WEB",
"url": "https://github.com/dep0we/atomic-agents-stack/releases#release-v1.1.0"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "atomic-agents-stack: HTTP MCP catalog accepts cleartext http and spawns catalog-supplied commands (MITM to RCE)"
}
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