Auth bypass in Presenton
CVE-2026-58446
Presenton before 0.8.8-beta bundles an MCP server that, on server/Docker deployments configured with session authentication (AUTH_USERNAME/AUTH_PASSWORD), is reachable unauthenticated at /mcp because the nginx front-end does not apply the auth_request gate to that path and the MCP server auto-mints a valid internal session token for the configured user. A remote unauthenticated attacker can invoke MCP tools such as generate_presentation, performing authenticated application actions, consuming the operators configured LLM API keys, and creating presentations in the operators instance. The Electron desktop build is not affected (MCP disabled).
Vulnerability class: Broken Authentication
EPSS: 0.004 (35.8th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L.
Affected products
- Presenton — versions 0
Weakness classification (CWE)
References
- disclosure@vulncheck.com (release-notes)
- disclosure@vulncheck.com (technical-description, exploit)
- disclosure@vulncheck.com (issue-tracking)
- disclosure@vulncheck.com (patch)
- disclosure@vulncheck.com (third-party-advisory)
Frequently asked questions
- What is CVE-2026-58446?
- CVE-2026-58446 is a medium-severity vulnerability in Presenton, classified under Missing Authentication for Critical Function. CVSS score: 6.5/10. Published 2026-06-30.
- How severe is CVE-2026-58446?
- Medium severity. CVSS v3 base score is 6.5 out of 10.