What is CVE-2017-16634?

CVE-2017-16634 is a critical-severity vulnerability in Joomla Joomla\!, classified under Improper Authentication. CVSS score: 9.8/10. Published 2017-11-10.

How severe is CVE-2017-16634?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Auth bypass in Joomla Joomla\!

CVE-2017-16634

In Joomla! before 3.8.2, a bug allowed third parties to bypass a user's 2-factor authentication method.

Vulnerability class: Broken Authentication

Published 2017-11-10 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.044 (91.0th percentile), scored 2026-09-30.

Low probability of exploitation in the next 30 days, but still tracked. 91st percentile — 91.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.044 · newest: 0.044 · change: 0.000

Affected products

Joomla Joomla\!

Weakness classification (CWE)

CWE-287 — Improper Authentication

References

www.securityfocus.com/bid/101701 (VDB Entry, Third Party Advisory, vdb-entry)
developer.joomla.org/security-centre/713-20171102-core-2-factor-authentication-… (Patch, Vendor Advisory)
www.securitytracker.com/id/1039757 (VDB Entry, Third Party Advisory, vdb-entry)

Frequently asked questions

What is CVE-2017-16634?: CVE-2017-16634 is a critical-severity vulnerability in Joomla Joomla\!, classified under Improper Authentication. CVSS score: 9.8/10. Published 2017-11-10.
How severe is CVE-2017-16634?: Critical severity. CVSS v3 base score is 9.8 out of 10.