# Countdown Block <= 1.5.0 - Authenticated (Contributor+) Site-Wide CSS Injection via Reusable Block 'ref'

- **ID:** WPSEC-2026-1754
- **Plugin:** Countdown Block (`countdown-block`), https://wordpress.org/plugins/countdown-block/
- **Affected versions:** from 1.2.3 before 1.5.1
- **Fixed in:** 1.5.1 (Update to 1.5.1 or later.)
- **Severity:** Medium 5.4 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N)
- **Weakness:** CWE-74
- **Usage among sites WPSec scans:** plugin Low, affected versions None seen (as of 2026-10-27)
- **Attack surface analysis:** https://attacksurface.wpsec.com/plugin/countdown-block
- **Fix released:** 2026-10-26
- **Published:** 2026-10-27
- **URL:** https://wpsec.com/vuln/WPSEC-2026-1754/

## Description

The Countdown Block plugin for WordPress is vulnerable to CSS Injection in all versions up to, and including, 1.5.0, due to missing validation of the core/block 'ref' attribute: any post ID was accepted as a reusable block, its block CSS was written to a public stylesheet, and the IDs were saved to a site-wide option whose stylesheets load on every front-end page. This makes it possible for authenticated attackers, with contributor-level access and above, to make CSS from an unpublished draft load on every page of the site, which can be used to deface pages or send page data to another host.

## References

- https://wpsec.com/vuln/WPSEC-2026-1754/
- https://plugins.svn.wordpress.org/countdown-block/tags/1.5.1/
- https://wordpress.org/plugins/countdown-block/

Source: WPSec, https://wpsec.com/vuln/WPSEC-2026-1754/

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.