CVE-2020-11069

Meta

• CVSS v3.1: AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C
• CWE-352
• CWE-346

Problem

It has been discovered that backend user interface and install tool are vulnerable to same-origin request forgery. A backend user can be tricked into interacting with a malicious resource an attacker previously managed to upload to the web server - scripts are then executed with the privileges of the victims' user session.

In a worst case scenario new admin users can be created which can directly be used by an attacker. The vulnerability is basically a cross-site request forgery (CSRF) triggered by a cross-site scripting vulnerability (XSS) - but happens on the same target host - thus, it’s actually a same-origin request forgery.

Malicious payload such as HTML containing JavaScript might be provided by either an authenticated backend user or by a non-authenticated user using a 3rd party extension - e.g. file upload in a contact form with knowing the target location.

The attacked victim requires an active and valid backend or install tool user sessions at the time of the attack to be successful.

Additional Considerations

The deployment of additional mitigation techniques is suggested as described below.

Sudo Mode Extension

This TYPO3 extension intercepts modifications to security relevant database tables, e.g. those storing user accounts or storages of the file abstraction layer. Modifications need to confirmed by again by the acting user with providing their password again - this technique is known as "sudo mode". This way unintended actions happening in the background can be mitigated.

• https://github.com/FriendsOfTYPO3/sudo-mode
• https://extensions.typo3.org/extension/sudo_mode

Content Security Policy

Content Security Policies tell (modern) browsers how resources served a particular site are handled - it also it possible to disallow script executions for specific locations. In a TYPO3 context it is suggested to disallow direct script execution at least for locations /fileadmin/ and /uploads/.

# in fileadmin/.htaccess
<IfModule mod_headers.c>
	Header add Content-Security-Policy "default-src 'self'; script-src 'none';"
</IfModule>

Credits

Thanks to Matteo Bonaker who reported this issue and to TYPO3 security team member Oliver Hader who fixed the issue.

References

• https://typo3.org/security/advisory/typo3-core-sa-2020-006

A victim's authenticated browser session is used to submit forged requests to an application that cannot distinguish them from legitimate ones. Typical impact: state-changing actions performed as the victim without their consent.

CVE-2020-11069 has a CVSS score of 8.0 (High). The vector is network-reachable, low privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (9.5.17, 10.4.2); upgrading removes the vulnerable code path.

Kodem intelligence

Update to TYPO3 versions 9.5.17 or 10.4.2 that mitigates the problem described.

1. What is CVE-2020-11069? CVE-2020-11069 is a high-severity cross-site request forgery (CSRF) vulnerability in typo3/cms-core (composer), affecting versions >= 9.0.0, < 9.5.17. It is fixed in 9.5.17, 10.4.2. A victim's authenticated browser session is used to submit forged requests to an application that cannot distinguish them from legitimate ones.
2. How severe is CVE-2020-11069? CVE-2020-11069 has a CVSS score of 8.0 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which packages are affected by CVE-2020-11069?
   • typo3/cms-core (composer) (versions >= 9.0.0, < 9.5.17)
   • typo3/cms (composer) (versions >= 10.0.0, < 10.4.2)
4. Is there a fix for CVE-2020-11069? Yes. CVE-2020-11069 is fixed in 9.5.17, 10.4.2. Upgrade to this version or later.
5. Is CVE-2020-11069 exploitable, and should I be worried? Whether CVE-2020-11069 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2020-11069 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2020-11069?
   • Upgrade typo3/cms-core to 9.5.17 or later
   • Upgrade typo3/cms-core to 10.4.2 or later
   • Upgrade typo3/cms to 10.4.2 or later
   • Upgrade typo3/cms to 9.5.17 or later