Restrict Usernames Emails Characters Plugin <= 5.0.3 - Unauthenticated Missing Authorization to Site-Wide Maintenance Mode (DoS) and Nicename Data Deletion via Bulk Nicename Update Actions
- ID
- WPSEC-2026-0985
- Plugin
- Restrict Usernames Emails Characters (restrict-usernames-emails-characters)
- Affected
- all versions before 5.1
- Remediation
- Update to 5.1 or later.
- CVSS 3.1
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
- Weakness
- CWE-862
- Usage
- Plugin Low · Affected versions None seen among sites WPSec scans, 2026-10-15
- Attack surface
- Restrict Usernames Emails Characters Plugin on WPSec AttackSurface
- Fix released
- Published
Description
The Restrict Usernames Emails Characters plugin for WordPress is vulnerable to unauthorized modification and loss of data via the bulk user_nicename update and process-removal actions in all versions up to, and including, 5.0.3, due to missing capability checks and nonce verification in the val() function (hooked to admin_init) and the wp__loaded() function (hooked to wp_loaded). This makes it possible for unauthenticated attackers to put the whole site into the plugin's maintenance mode, which returns a 503 error to every visitor and administrator for about ten minutes and can be repeated, to empty the plugin's custom author-slug (nicename) table, and to delete the stored state of a running nicename update process.
References
- https://wpsec.com/vuln/WPSEC-2026-0985/
- https://plugins.svn.wordpress.org/restrict-usernames-emails-characters/tags/5.1/
- https://wordpress.org/plugins/restrict-usernames-emails-characters/
Published by WPSec. Provided as is, without warranty. Corrections: contact us.
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