# HollerBox — Fast & Effective Popups & Lead-Generation <= 2.3.13 - Unauthenticated Insecure Direct Object Reference to Arbitrary Post Unpublishing via Popup REST Endpoints

- **ID:** WPSEC-2026-0577
- **Plugin:** HollerBox — Fast & Effective Popups & Lead-Generation (`holler-box`), https://wordpress.org/plugins/holler-box/
- **Affected versions:** from 2.0 before 2.3.15
- **Fixed in:** 2.3.15 (Update to 2.3.15 or later.)
- **Severity:** Medium 6.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L)
- **Weakness:** CWE-639
- **Usage among sites WPSec scans:** plugin Low, affected versions Low (as of 2026-10-07)
- **Attack surface analysis:** https://attacksurface.wpsec.com/plugin/holler-box
- **Fix released:** 2026-10-06
- **Published:** 2026-10-07
- **URL:** https://wpsec.com/vuln/WPSEC-2026-0577/

## Description

The HollerBox plugin for WordPress is vulnerable to Insecure Direct Object Reference in versions 2.0 up to, and including, 2.3.13. The public popup submission, impression and conversion REST endpoints load a popup from a user-supplied ID without checking that the post is a HollerBox popup, and loading a popup runs a legacy settings migration that saves changes to that post. This makes it possible for unauthenticated attackers to change the status of arbitrary posts, pages and other content to draft, taking them off the site, and to write HollerBox settings into their post meta. The submission endpoint also accepted submissions to unpublished popups, running their configured integrations.

## References

- https://wpsec.com/vuln/WPSEC-2026-0577/
- https://plugins.svn.wordpress.org/holler-box/tags/2.3.15/
- https://wordpress.org/plugins/holler-box/

Source: WPSec, https://wpsec.com/vuln/WPSEC-2026-0577/

License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Free to use, share and adapt, also commercially, if you credit WPSec and link to this advisory.