vulnerability / NVI-00005146 / Revision 3
October CMS vulnerable to Potential Host Header Poisoning on misconfigured servers
OSV carries this publisher advisory for october/backend. This is an aggregated source copy; consult the original publisher and compare update dates.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
4.3 MEDIUM (2.0)
nvd@nist.gov severity; no combined Null risk score.
6.8 MEDIUM (3.1)
security-advisories@github.com severity; no combined Null risk score.
7.5 HIGH (3.1)
nvd@nist.gov severity; no combined Null risk score.
1.748%
FIRST EPSS model v2026.06.15; exploitation probability over 30 days, percentile 0.77837. Missing scores are unknown.
As of · FIRST EPSS
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
october/backend
source listedECOSYSTEM: introduced 0; fixed 1.1.2
### 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
03 / Response
What to do next
- vendor patch
The original advisory lists fixed boundaries 1.1.2 for october/backend. Confirm the publisher’s latest guidance.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. GitHub Advisory Database via OSV
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. FIRST EPSS
A fixed release is not deployment evidence.
Check current vendor support and compatibility. After making a change, verify the deployed build and relevant runtime conditions. Keep the evidence, owner and time. An updated lockfile alone does not prove what is running.
04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
- NVD lastModified does not establish freshness of every associated CPE record.
05 / Provenance
Sources you can inspect
Each assertion retains its source. Mirrored records may repeat one underlying publisher; additional links are not independent corroboration.
- GHSA-xhfx-hgmf-v6vp ↗
GitHub Advisory Database via OSV · vendor advisory
Observed . GitHub-origin advisory, CC-BY-4.0; OSV is an aggregate copy, not independent corroboration.
- CVE-2021-21265 ↗
NIST National Vulnerability Database · official catalog
Observed . This product uses data from the NVD API but is not endorsed or certified by the NVD.
- CVE-2021-21265 ↗
FIRST EPSS · official catalog
Observed . FIRST EPSS; probability of exploitation in the next 30 days, not local compromise. Dataset date/model retained; FIRST services terms apply.
Public revision history
Only published revisions appear here. Routine fetches do not create a material-change event.
- Revision 3 ·
Dated EPSS estimate updated; this is not a new disclosure or proof of exploitation.
- Revision 2 ·
Source facts changed; compare the preserved prior revision.
- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.