Wagtail is an open source content management system built on Django. Prior to versions 4.1.4 and 4.2.2, a memory exhaustion bug exists in Wagtails handling of uploaded images and documents. For both images and documents, files are loaded into memory during upload for additional processing. A user with access to upload images or documents through the Wagtail admin interface could upload a file so large that it results in a crash of denial of service.
The vulnerability is not exploitable by an ordinary site visitor without access to the Wagtail admin. It can only be exploited by admin users with permission to upload images or documents.
Image uploads are restricted to 10MB by default, however this validation only happens on the frontend and on the backend after the vulnerable code.
Patched versions have been released as Wagtail 4.1.4 and Wagtail 4.2.2). Site owners who are unable to upgrade to the new versions are encouraged to add extra protections outside of Wagtail to limit the size of uploaded files.
The product does not properly control the allocation and maintenance of a limited resource.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Wagtail | Torchbox | * | 4.1.4 (excluding) |
| Wagtail | Torchbox | 4.2 (including) | 4.2.2 (excluding) |
Mitigation of resource exhaustion attacks requires that the target system either:
The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question.
The second solution is simply difficult to effectively institute – and even when properly done, it does not provide a full solution. It simply makes the attack require more resources on the part of the attacker.