Platform
joomla
Fixed in
4.0.1
6.0.1
CVE-2026-21631 describes a Cross-Site Scripting (XSS) vulnerability discovered in the multilingual associations component of Joomla. This vulnerability allows attackers to inject malicious scripts into the application, potentially compromising user sessions and website integrity. The issue affects Joomla versions 4.0.0 through 6.0.3, and a patch is available to address the flaw.
The XSS vulnerability in Joomla's multilingual associations component arises from insufficient output escaping. An attacker can craft a malicious payload and inject it into a vulnerable parameter, which is then rendered without proper sanitization. This allows the attacker to execute arbitrary JavaScript code in the context of the victim's browser. Successful exploitation could lead to session hijacking, allowing the attacker to impersonate legitimate users. Furthermore, the attacker could deface the website, redirect users to malicious sites, or steal sensitive information such as login credentials and personal data. The blast radius extends to all users interacting with the multilingual associations feature, particularly those who are logged in.
CVE-2026-21631 was publicly disclosed on 2026-04-01. Currently, there are no publicly available proof-of-concept exploits. The EPSS score is pending evaluation. Monitor security advisories and threat intelligence feeds for any indications of active exploitation campaigns targeting this vulnerability.
Exploit Status
EPSS
0.02% (5% percentile)
CISA SSVC
The primary mitigation for CVE-2026-21631 is to upgrade Joomla to a patched version. Joomla developers have released updates that address the output escaping issue. If immediate upgrading is not feasible, consider implementing a Web Application Firewall (WAF) rule to filter out potentially malicious input targeting the multilingual associations component. Carefully review and sanitize all user-supplied data before rendering it on the website. Regularly scan the website for XSS vulnerabilities using automated tools.
Update Joomla! to the latest available version. This will fix the XSS vulnerability in the multilingual associations component.
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CVE-2026-21631 is a Cross-Site Scripting (XSS) vulnerability in Joomla's multilingual associations component, allowing attackers to inject malicious scripts.
You are affected if your Joomla installation uses the multilingual associations component and is running versions 4.0.0 through 6.0.3.
Upgrade your Joomla installation to a patched version that addresses the vulnerability. Implement WAF rules as an interim measure.
Currently, there are no confirmed reports of active exploitation, but it's crucial to apply the patch promptly.
Refer to the official Joomla security advisory on their website for detailed information and updates.
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