- Component Type: TYPO3 CMS
- Vulnerable subcomponent: File List (ext:filelist)
- Release Date: January 22, 2019
- Vulnerability Type: Arbitrary Code Execution
- Affected Versions: 8.0.0-8.7.22 and 9.0.0-9.5.3
- Severity: None - Critical (depending on web server configuration)
- Suggested CVSS v3.0: AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:F/RL:O/RC:C
- CVE: not assigned yet
Problem Description
Due to missing file extensions in $GLOBALS['TYPO3_CONF_VARS']['BE'][‘fileDenyPattern’], backend users are allowed to upload *.phar, *.shtml, *.pl or *.cgi files which can be executed in certain web server setups. A valid backend user account is needed in order to exploit this vulnerability.
Derivatives of Debian GNU Linux are handling *.phar files as PHP applications since PHP 7.1 (for unofficial packages) and PHP 7.2 (for official packages).
The file extension *.shtml is bound to server side includes which are not enabled per default in most common Linux based distributions. File extension *.pl and *.cgi require additional handlers to be configured which is also not the case in most common distributions (except for /cgi-bin/ location).
Solution
Update to TYPO3 versions 8.7.23 or 9.5.4 to fix the problem described.
Credits
Thanks to Edgar Boda-Majer and Lauritz Holtmann who reported these issues and to TYPO3 core team member Oliver Hader 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.