Summary
Craft CMS has a potential RCE with a compromised security key
Workarounds
If you can't update to a patched version, then rotating your security key and ensuring its privacy will help to migitgate the issue.
References
https://github.com/craftcms/cms/commit/e59e22b30c9dd39e5e2c7fe02c147bcbd004e603
Impact
This is an RCE vulnerability that affects Craft 4 and 5 installs where your security key has already been compromised.
https://craftcms.com/knowledge-base/securing-craft#keep-your-secrets-secret
Anyone running an unpatched version of Craft with a compromised security key is affected.
Untrusted input is evaluated as executable code within the application's runtime environment. Typical impact: arbitrary code execution within the application's privilege context.
CVE-2025-23209 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 (5.5.8, 4.13.8); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
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. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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This has been patched in Craft 5.5.8 and 4.13.8.
Frequently Asked Questions
- What is CVE-2025-23209? CVE-2025-23209 is a high-severity code injection vulnerability in craftcms/cms (composer), affecting versions >= 5.0.0-RC1, < 5.5.5. It is fixed in 5.5.8, 4.13.8. Untrusted input is evaluated as executable code within the application's runtime environment.
- How severe is CVE-2025-23209? CVE-2025-23209 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.
- Which versions of craftcms/cms are affected by CVE-2025-23209? craftcms/cms (composer) versions >= 5.0.0-RC1, < 5.5.5 is affected.
- Is there a fix for CVE-2025-23209? Yes. CVE-2025-23209 is fixed in 5.5.8, 4.13.8. Upgrade to this version or later.
- Is CVE-2025-23209 exploitable, and should I be worried? Whether CVE-2025-23209 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
- What actually determines whether CVE-2025-23209 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.
- How do I fix CVE-2025-23209?
- Upgrade
craftcms/cmsto 5.5.8 or later - Upgrade
craftcms/cmsto 4.13.8 or later
- Upgrade