CVE-2021-26030 [20210401] - Core - Escape xss in logo parameter error pages

What is CVE-2021-26030?

CVE-2021-26030 is a medium-severity cross-site scripting vulnerability in Joomla Joomla\!, published on 14 Apr 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

Official description

An issue was discovered in Joomla! 3.0.0 through 3.9.25. Inadequate escaping allowed XSS attacks using the logo parameter of the default templates on error page

Weakness: CWE-79

Which versions are affected by CVE-2021-26030?

1 open source package ship an affected version, including joomla. It affects 1 product.

Products include Joomla Joomla\!.

How do I fix CVE-2021-26030?

No fix has been published for CVE-2021-26030 yet. Limit exposure of the affected software until one is available.

Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.

Is CVE-2021-26030 being exploited?

There is no known exploitation of CVE-2021-26030 in the wild and no public exploit code.

Other vulnerabilities in Joomla Joomla\!

• CVE-2016-10033 PHPMailer Command Injection Exploited Critical 9.8
• CVE-2023-23752 Joomla! Improper Access Control Exploited Medium 5.3
• CVE-2026-48902 Joomla! Core - [20260518] - Transport encryption downgrade for password and username reset links Critical 9.8
• CVE-2025-25226 [20250401] - Joomla Framework - SQL injection vulnerability in quoteNameStr method of Database package Critical 9.8
• CVE-2022-23795 [20220303] - Core - User row are not bound to a authentication mechanism Critical 9.8

All Joomla Joomla\! vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BIT-joomla-2021-26030, GHSA-f8r2-5wfg-hq3j.