Which products and versions are affected by CVE-2016-8870?

Affected: Joomla\!. The full list is in the CVE brief.

Is CVE-2016-8870 being exploited in the wild?

It is exploited in the wild, listed in Industry KEV feed since Oct 28, 2016.

Is CVE-2016-8870 in the CISA KEV catalog?

No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.

Is there a public exploit for CVE-2016-8870?

Public exploit code is available.

Is there a fix for CVE-2016-8870?

Fixed versions are available, including Joomla\! 3.6.3.

How urgently should CVE-2016-8870 be patched?

Brandefense priority: patch immediately, because it is listed as exploited in the wild.

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Vulnerability Intelligence

CVE-2016-8870

HighExploitedPublic exploit

The register method in the UsersModelRegistration class in controllers/user.php in the Users component in Joomla!

Published Nov 4, 2016 · Updated Jul 8, 2026

Key Facts

Patch immediately

CVE-2016-8870 is a high-severity vulnerability (CVSS 8.1 v3.1) affecting Joomla\!.
It is exploited in the wild, listed in Industry KEV feed since Oct 28, 2016. Public exploit code is available.
EPSS estimates a 81% probability of exploitation in the next 30 days.
Fixed versions are available, including Joomla\! 3.6.3.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.

CVSS v3.1

8.1

CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS (30-day exploit likelihood)

81%

Higher than 99.6% of all scored CVEs

Exploited in the wild

Yes

1 catalog listing

Public exploit code

Available

Proof-of-concept or weaponized module

Get the full CVE-2016-8870 brief as a PDF

Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.

Description

The register method in the UsersModelRegistration class in controllers/user.php in the Users component in Joomla! before 3.6.4, when registration has been disabled, allows remote attackers to create user accounts by leveraging failure to check the Allow User Registration configuration setting.

Known-Exploited Catalog Listings

Catalog	Added	Remediation due	Ransomware use
Industry KEV feed	Oct 28, 2016	n/a	Not reported

Required action: Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable.

Affected Products

1 affected entries in total

Product	Affected versions	Fixed in
Joomla\!Joomla	See advisory	3.6.3

Patched Releases

Joomla\!

3.6.3

Timeline

Added to Industry KEV feed
Oct 28, 2016
Publicly disclosed
Nov 4, 2016
Last updated
Jul 8, 2026

Weakness Type

CWE-20 Improper Input Validation

References

6 more references in the full CVE brief

FAQ

Common Questions.

The register method in the UsersModelRegistration class in controllers/user.php in the Users component in Joomla!
Affected: Joomla\!. The full list is in the CVE brief.
It is exploited in the wild, listed in Industry KEV feed since Oct 28, 2016.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
Public exploit code is available.
Fixed versions are available, including Joomla\! 3.6.3.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.

Is CVE-2016-8870 Running On Your Attack Surface?

Brandefense maps vulnerabilities like this one to your internet-facing assets and tells you exactly where to patch.