GiveWP < 4.16.1 - Authenticated (Author+) Stored Cross-Site Scripting via 'block_id' Shortcode Attribute

Description

The GiveWP – Donation Plugin and Fundraising Platform plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'block_id' (and other) shortcode attributes of the 'givewp_campaign_comments' shortcode in versions up to, and including, 4.16.0. This is due to insufficient input sanitization and output escaping on user supplied attributes in CampaignCommentsShortcode::parseAttributes() and BlockRenderController::render(), where the blockId value is interpolated directly into a single-quoted HTML attribute without esc_attr(). This makes it possible for authenticated attackers, with author-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.