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.linkPolicyis set toforce.
Alternative Workaround
Check to make sure that your web server does not accept any hostname when serving your web application.
- Add an entry called
testing.tldto your computer's host file and direct it to your server's IP address - Open the address
testing.tldin your web browser - 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">Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Composer package | october/backend | < 1.1.2 | 1.1.2 |
References
- https://github.com/octobercms/october/security/advisories/GHSA-xhfx-hgmf-v6vp
- https://nvd.nist.gov/vuln/detail/CVE-2021-21265
- https://github.com/octobercms/library/commit/f29865ae3db7a03be7c49294cd93980ec457f10d
- https://github.com/octobercms/library/commit/f86fcbcd066d6f8b939e8fe897409d152b11c3c6
- https://github.com/octobercms/october/commit/555ab61f2313f45d7d5d138656420ead536c5d30
- https://github.com/octobercms/october/commit/f638d3f78cfe91d7f6658820f9d5e424306a3db0
- https://packagist.org/packages/october/backend
- Weakness (CWE)
CWE-644- Platform
- Composer
- Package
october/backend- Disclosed
- 10.03.2021
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-xhfx-hgmf-v6vp - CC BY 4.0
Vulnerability history: october/backend
All published vulnerabilities of this package (Composer package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 7
- First → latest
- 06.2020 03.2021
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Medium 2
- Low 5
Disclosures per year
- 2020: 6
- 2021: 1
- 2022: 0
- 2023: 0
- 2024: 0
- 2025: 0
- 2026: 0
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October CMS vulnerable to Potential Host Header Poisoning on misconfigured servers this entry
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