CVE-2021-21265: October CMS vulnerable to Potential Host Header Poisoning on misconfigured servers
Impact When running on servers that are configured to accept a wildcard as a hostname (i.e. the server routes any request, regardless of the HOST header to an October CMS instance) the potential exists for Host Header Poisoning attacks to succeed. See the following resources for more information on Host Header Poisoning: - https://portswigger.net/web-security/host-header - https://dzone.com/articles/what-is-a-host-header-attack
Patches
A feature has been added in v1.1.2 to allow a set of trusted hosts to be specified in the application.
Workarounds
- Apply https://github.com/octobercms/library/commit/f86fcbcd066d6f8b939e8fe897409d152b11c3c6 & https://github.com/octobercms/october/commit/f638d3f78cfe91d7f6658820f9d5e424306a3db0 to your installation manually if unable to upgrade to v1.1.2.
- Check that the configuration setting cms.linkPolicy is set to force.
Alternative Workaround
Check to make sure that your web server does not accept any hostname when serving your web application.
1. Add an entry called testing.tld to your computer's host file and direct it to your server's IP address 2. Open the address testing.tld in your web browser 3. Make sure an October CMS website is not available at this address
If an October CMS website is returned, configure your webserver to only allow known hostnames. If you require assistance with this, please contact your server administrator.
References
Reported by Abdullah Hussam
For More Information
If you have any questions or comments about this advisory: Email us at hello@octobercms.com
Threat Assessment <img width="1108" alt="Screen Shot 2021-01-15 at 4 12 57 PM" src="https://user-images.githubusercontent.com/7253840/104783859-92fb3600-574c-11eb-9e21-c0dc05d230a9.png">
Other sources
October is a free, open-source, self-hosted CMS platform based on the Laravel PHP Framework. In October before version 1.1.2, when running on poorly configured servers (i.e. the server routes any request, regardless of the HOST header to an October CMS instance) the potential exists for Host Header Poisoning attacks to succeed. This has been addressed in version 1.1.2 by adding a feature to allow a set of trusted hosts to be specified in the application. As a workaround one may set the configuration setting cms.linkPolicy to force.
— MITRE
Affected Software
Remediation
Event History
Frequently Asked Questions
What is CVE-2021-21265?
CVE-2021-21265 is a vulnerability in October, a free open-source self-hosted CMS platform based on the Laravel PHP Framework, before version 1.1.2.
What is the severity of CVE-2021-21265?
The severity of CVE-2021-21265 is high with a CVSS score of 7.5.
How does CVE-2021-21265 impact October?
CVE-2021-21265 can allow an attacker to cause a potential security issue when October is running on poorly configured servers.
How can I fix CVE-2021-21265?
To fix CVE-2021-21265, it is recommended to update to version 1.1.2 or later of October CMS.
Where can I find more information about CVE-2021-21265?
More information about CVE-2021-21265 can be found on the October CMS GitHub page and the associated security advisories.