Pimcore is an Open Source Data & Experience Management Platform. The Pimcore thumbnail generation can be used to flood the server with large files. By changing the file extension or scaling factor of the requested thumbnail, attackers can create files that are much larger in file size than the original. This vulnerability is fixed in 11.2.4.

Affected: Packagist: pimcore/pimcore

# Details ## 1. All Imagick supported Fileformats are served without filtering

The Thumbnail endpoint does not check against any filters what file formats should be served. We can transcode the image in all formats imagemagick supports. With that we can create Files that are much larger in filesize than the original. For example we can create a .txt file for all thumbnails, and we get the text representation of the image.

We can demonstrate that with the pimcore demo:

This Thumbnail is found on the Frontend: https://demo.pimcore.fun/Sample%20Content/Background%20Images/317/image-thumb__317__standardTeaser/11.8c64bd89.avif (12kb Filesize)

We can generate a text representation by simply changing the file extension: https://demo.pimcore.fun/Sample%20Content/Background%20Images/317/image-thumb__317__standardTeaser/11.8c64bd89.txt (4.59mb Filesize)

Other (large) fileformats we tested: ftxt, dip, bmp, bmp3, bmp2, farbfeld, cmyk, cmyka, ycbcr, ycbcra and many more (just check imagemagick supported formats)

With that we can fill the available space of a server really easy.

With formats like yaml or json we can also expose exif data of the original image file - could be a concern with gps data in user uploaded images.

### TLDR

- we can generate all imagemagick supported formats with all thumbnail configs - all configs were the format is set to "auto (Web-optimized)" are vulnerable - private (exif) data can be exposed. - We can flood the the server with a bunch of files that…