Quick answers
- Is CVE-2026-81766 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-81766 being exploited in the wild.
- How severe is CVE-2026-81766?
- Medium severity, with a CVSS score of 6.6, published 30 August 2026.
- Which products and versions are affected?
- Really Simple Plugins Really Simple Security before 9.8.0.
- Is there a fix for CVE-2026-81766?
- A patch was published on 2026-08-30: Version 9.8.0 fixes the authorization bypass Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-81766 attacked?
- It is attacked over the network, in a software library.
- Am I affected by CVE-2026-81766?
- Check whether you run Really Simple Plugins Really Simple Security at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
The vulnerability is an authorization bypass (CWE-269) in the rsp_upgrade_install_plugin AJAX action. The plugin fails to verify that the current user has permission to install plugins before downloading and installing a plugin from a user-supplied URL. An authenticated subsite administrator can craft a request with a valid CSRF token from the plugins page and specify an attacker-controlled ZIP file URL. The malicious plugin is then extracted to the network-shared wp-content/plugins directory, making it active across all sites in the network. Exploitation requires: (1) WordPress multisite configuration, (2) the Plugins menu enabled for subsites in network settings (non-default), and (3) the attacker being a subsite administrator. The issue was patched in version 9.8.0.
Affected products
- Really Simple Plugins Really Simple Security before 9.8.0
Timeline
- 2026-08-28: disclosed
- 2026-08-30: patched: Version 9.8.0 fixes the authorization bypass