CVE-2021-21265
MEDIUMEPSS 76th pctlDescription
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.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:H/A:N
Exploit Intelligence
Elevated risk: more likely to be exploited than 76% of all known CVEs.
References
Related Vulnerabilities
Other CWE-644 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2017-6031 | High | 8.8 | 2.8% | - | - |
| CVE-2021-41114 | Medium | 4.8 | 1.2% | - | Fix |
| CVE-2021-20784 | Medium | 6.1 | 1.1% | - | Fix |
| CVE-2020-6982 | High | 8.8 | 1.1% | - | - |
| CVE-2024-1064 | High | 7.5 | 0.8% | - | - |
| CVE-2023-47143 | Critical | 10.0 | 0.8% | - | Fix |
Common questions
How do I fix CVE-2021-21265?
Upgrade october to 1.1.2 or later.
Is CVE-2021-21265 being actively exploited?
Not that we know of. CVE-2021-21265 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 1.7% is the estimated probability that it will be exploited in the next 30 days. That is higher than 76% of all scored CVEs.
How severe is CVE-2021-21265?
CVE-2021-21265 has a CVSS v3 base score of 6.8, rated medium. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2021-21265 affect?
Published advisories record a fix for october (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
Embed a live status badge for CVE-2021-21265
Markdown
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TridentStack Control continuously scans your Windows, macOS, and Linux fleet for known vulnerabilities, prioritizes them by severity and active exploitation, and patches them automatically.
This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-05-30.