Full Read Server-Side Request Forgery (SSRF) in kareadita/kavita


Reported on

Aug 6th 2022


Via the /api/upload/upload-by-url endpoint is possible to upload an image via an URL provided by the user. The function that handles this upload, doesn't verify or validate the provided URL, allowing to fetch internal services.

Furthermore, after the resource is fetched, there is no MIME type validation, which would ensure that the resource is indeed an image. Then, the file is saved to a temporary directory, that can be retrieved via the /api/image/cover-upload API endpoint.

Finally, an attacker can manipulate the extension of the saved file, by adding the the hash sign # to the end of the URL and then an extension of its choice, for example.png .This in important because it doesn't modify the internal fetched resource, but allows to save the response to a valid file, that can be successfully retrieved via the /api/image/cover-upload endpoint.

Proof of Concept

For testing purposes, I started an internal-only HTTP server, listening at port 8000, along side the application.

1 - Login in the application.
2 - Send the following request, where the url attribute is the target resource, in this case will be the HTTP server at port 8000. ssrf-1 3 - Visit the /api/image/cover-upload?filename=<filename> URL, where the filename contains the above response filename. ssrf-2


An attacker can get sensitive information of any internal-only services running. For example, if the application is hosted on Amazon Web Services (AWS) plataform, its possible to fetch the AWS API endpoint,, which returns API keys and other sensitive metadata.

We are processing your report and will contact the kareadita/kavita team within 24 hours. 2 years ago
We created a GitHub Issue asking the maintainers to create a SECURITY.md 2 years ago
We have contacted a member of the kareadita/kavita team and are waiting to hear back 2 years ago
Joe Milazzo validated this vulnerability 2 years ago

Fixed locally

vultza has been awarded the disclosure bounty
The fix bounty is now up for grabs
The researcher's credibility has increased: +7
Joe Milazzo marked this as fixed in with commit 9c31f7 2 years ago
Joe Milazzo has been awarded the fix bounty
UploadController.cs#L50-L72 has been validated
2 years ago


@admin Would be possible to issue an CVE ID on this report? Thanks.

Jamie Slome
2 years ago

CVE sorted 👍

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