High severity · published Jul 7, 2021
CVE-2021-26036
An issue was discovered in Joomla! 2.5.0 through 3.9.27
7.5
CVSS
1.2%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)1.2% · higher than 69% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
JO
Joomla · Joomla
2.5.0 through 3.9.27 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-26036
CVE.org
https://www.cve.org/CVERecord?id=CVE-2021-26036
Vendor Advisory
https://developer.joomla.org/security-centre/857-20210702-core-dos-through-usergroup-table-manipulation.html
More from Joomla
9.8
CVE-2016-10033
The mailSend function in the isMail transport in PHPMailer before 5.2.18 might allow remote attackers to pass extra parameters to the mail command and consequently execute…
5.3
CVE-2023-23752
[20230201] - Core - Improper access check in webservice endpoints
9.8
CVE-2026-73373
Joomla! Core - [20260810] - Unrestricted uploads of SHTML files in Joomla 1.0.0-5.4.7, 6.0.0-6.1.2
9.8
CVE-2026-35221
Joomla! Core - [20260506] - Authenticated blind SQLi in com_finder
9.8
CVE-2026-40383
Joomla! Core - [20260509] - LFI in HTMLView layout parameter