Component Type: TYPO3 CMS
Release Date: September 5, 2017
Vulnerability Type: Arbitrary Code Execution
Affected Versions: 7.6.0 to 7.6.21 and 8.0.0 to 8.7.4
Severity: None - High (depending on web server configuration)
Suggested CVSS v2.0: AV:N/AC:L/Au:S/C:C/I:C/A:C/E:F/RL:OF/RC:C
CVE: not assigned yet
Problem Description: Due to a missing file extension in the fileDenyPattern, backend user are allowed to upload *.pht files which can be executed in certain web server setups. The new default fileDenyPattern is the following, which might have been overridden in the TYPO3 Install Tool.
Solution: Update to TYPO3 versions 7.6.22 or 8.7.5 that fix the problem described, make sure overridden settings for TYPO3_CONF_VARS/BE/fileDenyPattern are adjusted.
Credits: Thanks to Maurizio Siddu who reported this issue and to TYPO3 core team member Susanne Moog who fixed the issue.
General Note: All security related code changes are tagged so that you can easily look them up on our review system.