Improper Authorization in GitHub repository wallabag/wallabag prior to 2.5.3.

Affected: Packagist: wallabag/wallabag

# Description

The export feature lets a user export a single entry or a set of entries in a given format (_e.g. PDF, MOBI, TXT_).

For example, `https://yourinstance.wallabag.org/export/45.pdf` will export the entry with id 45 in PDF format.

Since wallabag 2.0.0-alpha.1, this feature is vulnerable to an insecure direct object reference attack. A logged user can export any single entry without ownership validation.

This is due to a lack of access validation in the `downloadEntryAction` method.

**You should immediately patch your instance to version 2.5.3 or higher if you have more than one user and/or having open registration.**

# Resolution

A user check is now done in the vulnerable method before sending the exported entry.

The `Entry` retrieval through a `ParamConverter` has also been replaced with a call to the `EntryRepository` in order to prevent any information disclosure through response discrepancy.

# Workaround

If you are unable to update to the latest version or if you want to temporarily limit risk of exploitation, you may consider blocking requests to the endpoint `/export/*`.

E.g. with nginx:

``` nginx location /export { deny all; } ```

# Credits

We would like to thank @bAuh0lz for reporting this issue through huntr.dev.

Reference: https://www.huntr.dev/bounties/3adef66f-fc86-4e6d-a540-2ffa59342ff0/