CVE-2021-26036 [20210702] - Core - DoS through usergroup table manipulation
Attackers can cause a denial of service in Joomla by manipulating the usergroups table due to missing input validation.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2021-26036?
CVE-2021-26036 is a high-severity denial of service vulnerability in Joomla Joomla\!, published on 7 Jul 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
An issue was discovered in Joomla! 2.5.0 through 3.9.27. Missing validation of input could lead to a broken usergroups table.
Weakness: CWE-20
Which versions are affected by CVE-2021-26036?
1 open source package ship an affected version, including joomla. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
joomla Bitnami | From 2.5.0 to 3.9.27 | None |
Products include Joomla Joomla\!.
How do I fix CVE-2021-26036?
No fix has been published for CVE-2021-26036 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2021-26036 being exploited?
There is no known exploitation of CVE-2021-26036 in the wild and no public exploit code.
Other vulnerabilities in Joomla Joomla\!
- CVE-2016-10033 PHPMailer Command Injection
- CVE-2023-23752 Joomla! Improper Access Control
- CVE-2026-48902 Joomla! Core - [20260518] - Transport encryption downgrade for password and username reset links
- CVE-2025-25226 [20250401] - Joomla Framework - SQL injection vulnerability in quoteNameStr method of Database package
- CVE-2022-23795 [20220303] - Core - User row are not bound to a authentication mechanism
Sources
Also known as BIT-joomla-2021-26036, GHSA-g983-3grj-v7qw.