Arbitrary file upload in Drupal - CVE-2020-13671
Published: November 18, 2020 / Updated: February 20, 2022
Vulnerability identifier: #VU48540
CSH Severity: High
CVSS v4: 9.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2020-13671
CWE-ID: CWE-434
Exploitation vector: Remote access
Exploit availability:
The vulnerability is being exploited in the wild
Vulnerability details
The vulnerability allows a remote attacker to compromise vulnerable system.
The vulnerability exists due to insufficient validation of file during file upload. A remote attacker can upload a malicious PHP file and execute it on the server.
Additionally, it's recommended that you audit all previously uploaded
files to check for malicious extensions. Look specifically for files
that include more than one extension, like .php.txt or .html.gif.
Pay specific attention to the following file extensions, which should
be considered dangerous even when followed by another extension:
- phar
- php
- pl
- py
- cgi
- asp
- js
- html
- htm
Affected software
Drupal
Backdrop CMS
drupal7 (Alpine package)
drupal7 (Ubuntu package)
drupal8
Ubuntu
Fedora
Backdrop CMS
drupal7 (Alpine package)
drupal7 (Ubuntu package)
drupal8
Ubuntu
Fedora
How to mitigate CVE-2020-13671
Install updates from vendor's website.
Drupal - addressed in versions 7.74, 8.8.11, 8.9.9, 9.0.8
Backdrop CMS - addressed in versions 1.16.5, 1.17.3
drupal7 (Alpine package) - update to 7.74-r0
drupal7 (Ubuntu package) - update to Ubuntu Pro
drupal8 - addressed in versions 8.9.11-1.fc32, 8.9.11-1.fc33
Backdrop CMS - addressed in versions 1.16.5, 1.17.3
drupal7 (Alpine package) - update to 7.74-r0
drupal7 (Ubuntu package) - update to Ubuntu Pro
drupal8 - addressed in versions 8.9.11-1.fc32, 8.9.11-1.fc33