• Component Type: TYPO3 CMS
• Vulnerable subcomponent: Link Handling (ext:core)
• Release Date: June 25, 2019
• Vulnerability Type: Cross-Site Scripting
• Affected Versions: 8.3.0-8.7.26 and 9.0.0-9.5.7
• Severity: Medium
• Suggested CVSS v3.0: AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N/E:F/RL:O/RC:C
• CVE: CVE-2019-12748

Problem Description

It has been discovered that the t3:// URL handling is vulnerable to cross-site scripting when making use of javascript: or data: scheme in link fields like the following.

t3://url/?url=javascript:alert(1);

Not only regular backend forms are affected but also frontend extensions which use the rendering with typolink.

Solution

Update to TYPO3 versions 8.7.27 or 9.5.8 that fix the problem described.

Credits

Thanks to Robin Peraglie (RIPS technologies) who reported this issue and to TYPO3 core team members Oliver Hader, Andreas Fernandez and Frank Nägler who fixed the issue.

General Advice

Follow the recommendations that are given in the TYPO3 Security Guide. Please subscribe to the typo3-announce mailing list.

General Note

All security related code changes are tagged so that you can easily look them up in our review system.