What is CVE-2021-23128?

CVE-2021-23128 is a critical-severity vulnerability in Joomla Joomla\!. CVSS score: 9.1/10. Published 2021-03-04.

How severe is CVE-2021-23128?

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

Vulnerability in Joomla Joomla\!

CVE-2021-23128

An issue was discovered in Joomla! 3.2.0 through 3.9.24. The core shipped but unused randval implementation within FOF (FOFEncryptRandval) used an potential insecure implemetation. That has now been replaced with a call to 'random_bytes()' and its backport that is shipped within random_compat.

Published 2021-03-04 · last modified 2026-06-17.

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.

EPSS exploit prediction

EPSS: 0.014 (71.0th percentile), scored 2026-09-30.

Low probability of exploitation in the next 30 days, but still tracked. 71st percentile — 71.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.013 · newest: 0.014 · change: +0.000

Affected products

Joomla Joomla\!
Joomla! Project Cms — versions 3.2.0-3.9.24

References

developer.joomla.org/security-centre/842-20210302-core-potential-insecure-fofen… (vendor-advisory, Vendor Advisory)

Frequently asked questions

What is CVE-2021-23128?: CVE-2021-23128 is a critical-severity vulnerability in Joomla Joomla\!. CVSS score: 9.1/10. Published 2021-03-04.
How severe is CVE-2021-23128?: Critical severity. CVSS v3 base score is 9.1 out of 10.