Instance Owners: Do Not Use Lemmy-Thumbnail-Cleaner

submitted by taaz edited

If you are using https://github.com/wereii/lemmy-thumbnail-cleaner please stop and disable it as soon as possible.

We have found a security issue that allows any user to make LTC delete any locally hosted image.

I will be posting more details soon and editing this to include the information.

E: More information here https://github.com/wereii/lemmy-thumbnail-cleaner/issues/10

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Emotet , edited

Ah. So Lemmy with version 0.19.4+ allows users to set a custom thumbnail URL for a post, which can be set to pretty much anything resembling a valid link, especially a link to another image in the local pictrs db and trigger a deletion of both when a minimum age check is passed.

Also this:

Except that the field allows some funny URLs e.g. https://t.t/;';'%22;...[:%3C%3E?]%27;%20yaba%20daba%20doo, if this is an issue too is not confirmed

Relevant XKCD

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taaz [OP]

On point summary.
And I was just about to write that I have confirmed SQLi is not possible to find out I have missed something that might in-turn make it possible! holy hell back to drawing board

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Emotet

Yikes. Thanks for putting in the works and sharing your findings to you and @Nothing4You@programming.dev.

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db0

I'm really curious how someone can exploit a script that is meant to be running locally with no external facing interface

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taaz [OP]

Post edited with link to more information.

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db0

thanks

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