GHSA-xhcr-cqfr-m3hv

Source

https://github.com/advisories/GHSA-xhcr-cqfr-m3hv

Import Source

https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/08/GHSA-xhcr-cqfr-m3hv/GHSA-xhcr-cqfr-m3hv.json

JSON Data

https://api.osv.dev/v1/vulns/GHSA-xhcr-cqfr-m3hv

Aliases

CVE-2026-91988

Published

2026-08-17T21:49:55Z

Modified

2026-09-16T03:56:06Z

Severity

8.7 (High) CVSS_V4 - 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 CVSS Calculator

Summary

atomic-agents-stack: HTTP MCP catalog accepts cleartext http and spawns catalog-supplied commands (MITM to RCE)

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.

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.

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"
}

References

Affected packages

PyPI / atomic-agents-stack

Package

Name: atomic-agents-stack; View open source insights on deps.dev
Purl: pkg:pypi/atomic-agents-stack

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0 Unknown introduced version / All previous versions are affected

Fixed

1.1.0

Affected versions

1.*

1.0.0

Database specific

last_known_affected_version_range

"<= 1.0.0"

source

"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/08/GHSA-xhcr-cqfr-m3hv/GHSA-xhcr-cqfr-m3hv.json"