Charitable <= 1.8.11.1 - Authenticated (Subscriber+) Insecure Direct Object Reference to Arbitrary Attachment Deletion via 'avatar' Parameter

The Charitable – Donation Plugin for WordPress – Fundraising with Recurring Donations & More plugin for WordPress is vulnerable to Insecure Direct Object Reference / Authorization Bypass leading to Arbitrary Attachment Deletion in versions up to, and including, 1.8.11.1 via the profile avatar update flow. This is due to the save_avatar() function in Charitable_Profile_Form calling wp_delete_attachment() on an attachment ID read from the user's 'avatar' meta without validating that the attachment is owned by the user, combined with Charitable_Data_Processor::process_picture() returning the raw posted value when no file is uploaded, allowing the 'avatar' user meta to be poisoned with any attacker-chosen attachment ID. This makes it possible for authenticated attackers, with Subscriber-level access and above, to delete arbitrary attachments from the Media Library by performing a two-request chain (first poisoning the stored avatar meta value with a target attachment ID, then triggering deletion via a normal avatar upload).