CVE-2021-23126Network attack vector

TOTP secret guessing via weak random generation

Published Mar 4, 2021 · Updated Feb 25, 2026

Weak randomness in Joomla! CMS 3.2.0 through 3.9.24 allows attackers to narrow the candidate space for newly generated TOTP secrets. Joomla\CMS\Encrypt\Totp::generateSecret uses PHP rand() instead of a cryptographically secure generator when it creates the shared 2FA secret. Exploitation requires knowing the approximate secret-generation time; Joomla reports that millions of candidates remain and practical risk is low.

CVSS severity5.3
Medium
EPSS probability1.07%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Weak randomness in Joomla! CMS 3.2.0 through 3.9.24 allows attackers to narrow the candidate space for newly generated TOTP secrets. Joomla\CMS\Encrypt\Totp::generateSecret uses PHP rand() instead of a cryptographically secure generator when it creates the shared 2FA secret. Exploitation requires knowing the approximate secret-generation time; Joomla reports that millions of candidates remain and practical risk is low.

The record

CVE
CVE-2021-23126
Published
Mar 4, 2021
Updated
Feb 25, 2026
Vendor
Joomla! Project
Product
Joomla! CMS
Classifications
CWE-338, T1110
Attack vector
network
Privileges
Unavailable

Timeline

How it unfolded

  1. Mar 4, 2021CVE publishedPublication date reported by the CVE source.
  2. Feb 25, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=3.2.0-3.9.24

What conditions does exploitation require?

Attack vectornetwork
Required privilegesUnavailable in this record.

What is affected?

Joomla! Project · Joomla! CMSversion=3.2.0-3.9.24

Published CVSS scores

5.0NIST NVDAV:N/AC:L/Au:N/C:P/I:N/A:N
5.3NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-338Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)
T1110Brute Force

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo