What is CVE-2026-48039?

CVE-2026-48039 is a critical-severity vulnerability in Pipeboard-Co Meta-Ads-Mcp, classified under Improper Authentication. CVSS score: 9.1/10. Published 2026-08-07.

How severe is CVE-2026-48039?

Critical severity. CVSS v3 base score is 9.1 out of 10.

Auth bypass in Pipeboard-Co Meta-Ads-Mcp

CVE-2026-48039

Meta Ads MCP is a Model Context Protocol (MCP) server that lets AI assistants run Meta Ads. Prior to version 1.0.109, `AuthInjectionMiddleware.dispatch()` at `http_auth_integration.py:272` unconditionally forwards unauthenticated Streamable HTTP requests to downstream MCP tool handlers without issuing a `401` response, allowing any network-reachable caller to invoke MCP tools without authentication. When no per-request credential is present, tool handlers fall back to the `META_ACCESS_TOKEN` environment variable, and when the downstream Meta Graph API call fails, `api.py:263–269` serialises the raw `httpx` request URL—including the operator's `access_token` as a query parameter—into the JSON-RPC response body, delivering the credential to the unauthenticated caller. Version 1.0.109 fixes the issue.

Vulnerability class: Broken Authentication

EPSS: 0.004 (36.4th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.

Affected products

Pipeboard-co Meta-ads-mcp — versions < 1.0.109

Weakness classification (CWE)

CWE-287 — Improper Authentication

References

security-advisories@github.com (x_refsource_CONFIRM)
security-advisories@github.com (x_refsource_MISC)
security-advisories@github.com (x_refsource_MISC)

Frequently asked questions

What is CVE-2026-48039?: CVE-2026-48039 is a critical-severity vulnerability in Pipeboard-Co Meta-Ads-Mcp, classified under Improper Authentication. CVSS score: 9.1/10. Published 2026-08-07.
How severe is CVE-2026-48039?: Critical severity. CVSS v3 base score is 9.1 out of 10.