EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
pimcore/pimcoreReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
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 are a multiple magnitudes of the original thumbnail size (see txt example), for all thumbnail configs, with every image that we find (scriptable)
Proposed Solution
Implement a list of allowed formats that the developer can modify if needed, if a file is requested in another format than listed, pimcore should return either "/bundles/pimcoreadmin/img/filetype-not-supported.svg" or a 404.
pimcore:
thumbnails:
allowed_formats: ['jpg', 'png', 'avif', 'webp', 'gif']
For non-maintained Pimcore versions (<11), the webserver config could be used to only serve files that should be allowed.
2. Non Web optimized file formats (ORIGINAL, JPG, PNG) creates duplicated files on Server
With Thumbnail config that are configured to serve non web optimized file formats (such as ORIGINAL, jpg, png, print, etc) we can create files with arbitrary file formats that are saved to disk.
For example, the thumbnail configuration "print_backgroundimage" (in the pimcore demo) can be used to create files such as:
https://demo.pimcore.fun/Car%20Images/jaguar/3/image-thumb__3__print_backgroundimage/auto-3095119.aaa https://demo.pimcore.fun/Car%20Images/jaguar/3/image-thumb__3__print_backgroundimage/auto-3095119.aab https://demo.pimcore.fun/Car%20Images/jaguar/3/image-thumb__3__print_backgroundimage/auto-3095119.aac
Each request creates a new copy of the original (jpg) thumbnail file. The server can be flooded with a bunch of files.
Code for this mechanism is here: https://github.com/pimcore/pimcore/blob/11.x/models/Asset/Service.php#L621-L623
Proposed Solution
Use same filtered list from "All Imagick supported Fileformats are served without filtering" and do not copy the arbitrary file to disk, just serve the original image file under the "new" name.
3. Scaling Factor is not limited and can be modified via url
We can scale each thumbnail to an arbitrary factor with @<float>x added to the request url.
For example:
https://demo.pimcore.fun/Sample%20Content/Background%20Images/317/image-thumb__317__standardTeaser/[email protected] https://demo.pimcore.fun/Sample%20Content/Background%20Images/317/image-thumb__317__standardTeaser/[email protected] https://demo.pimcore.fun/Sample%20Content/Background%20Images/317/image-thumb__317__standardTeaser/[email protected] https://demo.pimcore.fun/Sample%20Content/Background%20Images/317/image-thumb__317__standardTeaser/[email protected]
If the thumbnail config allows "forced" resizing, we could also do something like:
Each request will create a new file, flooding the server with more files. If the factor is big enough, we can also max out the CPU with a single request for quite some time (only really a problem with "forced")
In combination with the first vulnerability we can also generate (large) text files for scaled images:
https://demo.pimcore.fun/Sample%20Content/Background%20Images/317/image-thumb__317__standardTeaser/[email protected] (6.6 mb filesize)
Proposed solution
Limit scale factors with an allowlist:
pimcore:
thumbnails:
allowed_scale_factors: [1.25, 1.5, 2, 4]
Impact
All Pimcore Instances are affected, as far as we can see, also all versions
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | pimcore/pimcore | ≥ 11.0.0&&< 11.2.4 | 11.2.4 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for pimcore/pimcore. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update pimcore/pimcore to 11.2.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-277c-5vvj-9pwx is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-277c-5vvj-9pwx is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-277c-5vvj-9pwx. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-277c-5vvj-9pwx in your dependencies?
O3 detects GHSA-277c-5vvj-9pwx across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.