High · published January 6, 2026
⚡ An administrator with a not-so-great sense of security can trigger a disaster! Craft versions 5.0.0-RC1 to 5.8.20 and 4.0.0-RC1 to 4.16.16 have a sneaky remote code execution vulnerability lurking in attached Behaviors. 🔥 Think of it like a chef with unrestricted access to the kitchen; if they don't check the ingredients, a rogue spice could spoil the entire dish. In this case, an attacker with admin access could mix in malicious code without anyone noticing! If exploited, this vulnerability could give attackers the keys to the kingdom, allowing them to execute any code within the system. Imagine an unwanted guest taking over the kitchen and serving up whatever they like, potentially leading to data breaches or system instability. It's a scenario nobody wants in their digital kitchen!
Think of it like a chef with unrestricted access to the kitchen; if they don't check the ingredients, a rogue spice could spoil the entire dish. In this case, an attacker with admin access could mix in malicious code without anyone noticing! Versions of Craft from 5.0.0-RC1 through 5.8.20 and 4.0.0-RC1 through 4.16.16 allow authenticated remote code execution due to improperly validated attached Behaviors. An attacker with admin access can leverage this flaw to run arbitrary code on the server.
If exploited, this vulnerability could give attackers the keys to the kingdom, allowing them to execute any code within the system. Imagine an unwanted guest taking over the kitchen and serving up whatever they like, potentially leading to data breaches or system instability. It's a scenario nobody wants in their digital kitchen! Update your Craft installation to versions 5.8.21 or 4.16.17 to patch this vulnerability immediately. Additionally, consider reviewing who has admin access to the Craft Control Panel and tighten security measures where necessary. Don't overlook this! You've got this! By following these steps, you'll keep your digital kitchen safe and secure! 🛡️
| Product | Versions | Fixed in |
|---|---|---|
| craftcms/craft_cms | ≥ 4.0.0.1, < 4.16.17 | 4.16.17 |
| craftcms/craft_cms | ≥ 5.0.1, < 5.8.21 | 5.8.21 |
| craftcms/craft_cms | all versions | — |
| craftcms/craft_cms | all versions | — |
| craftcms/craft_cms | all versions | — |
| craftcms/craft_cms | all versions | — |
| craftcms/craft_cms | all versions | — |
| craftcms/craft_cms | all versions | — |