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
Published · last modified .
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.
EPSS exploit prediction
EPSS: 0.007 (51.4th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 51st percentile — 51.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.007 · newest: 0.007 · change: 0.000
Affected products
- Presenton — versions 0
Weakness classification (CWE)
References
- github.com/presenton/presenton/releases/tag/electron-v0.8.8-beta (release-notes)
- github.com/presenton/presenton/issues/678 (technical-description, exploit)
- github.com/presenton/presenton/pull/679 (issue-tracking)
- github.com/presenton/presenton/commit/a1103dcef3c761cc8bab44e2862c81a49969abd7 (patch)
- www.vulncheck.com/advisories/presenton-beta-authentication-bypass-of-session-au… (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.