Summary
Craft CMS has potential authenticated Remote Code Execution via Twig SSTI
For this to work, the attacker must have administrator access to the Craft Control Panel, and allowAdminChanges must be enabled, which is against Craft CMS' recommendations for any non-dev environment.
https://craftcms.com/knowledge-base/securing-craft#set-allowAdminChanges-to-false-in-production
Alternatively, they can have a non-administrator account with allowAdminChanges disabled, but they must have access to the System Messages utility.
It is possible to craft a malicious payload using the Twig map filter in text fields that accept Twig input under Settings in the Craft control panel or using the System Messages utility, which could lead to a RCE.
Users should update to the patched versions (5.8.22 and 4.16.18) to mitigate the issue.
References:
Impact
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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craftcms/cms to 5.9.0-beta.1 or later; craftcms/cms to 4.17.0-beta.1 or later
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2026-28784? CVE-2026-28784 is a medium-severity security vulnerability in craftcms/cms (composer), affecting versions >= 5.0.0-RC1, < 5.9.0-beta.1. It is fixed in 5.9.0-beta.1, 4.17.0-beta.1.
- Which versions of craftcms/cms are affected by CVE-2026-28784? craftcms/cms (composer) versions >= 5.0.0-RC1, < 5.9.0-beta.1 is affected.
- Is there a fix for CVE-2026-28784? Yes. CVE-2026-28784 is fixed in 5.9.0-beta.1, 4.17.0-beta.1. Upgrade to this version or later.
- Is CVE-2026-28784 exploitable, and should I be worried? Whether CVE-2026-28784 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-2026-28784 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-2026-28784?
- Upgrade
craftcms/cmsto 5.9.0-beta.1 or later - Upgrade
craftcms/cmsto 4.17.0-beta.1 or later
- Upgrade