Description

Unauthenticated Bypass Vulnerability in SiteGround Security <= 1.6.6 versions.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "8.1",
  "pubDate": "2026-08-31T21:17:53.570Z",
  "pubdate": "2026-08-31T21:17:53.570Z",
  "executiveSummary": "The SiteGround Security plugin for WordPress, in versions 1.6.6 and below, contains an unauthenticated security bypass vulnerability.\nThis flaw allows remote, unauthenticated attackers to circumvent security controls implemented by the plugin, potentially leading to unauthorized access or the bypass of security restrictions configured within the WordPress environment.\nThe vulnerability poses a significant risk to the integrity and security posture of affected WordPress installations, as it enables attackers to circumvent intended security measures without requiring valid credentials.\nSuccessful exploitation requires no authentication, allowing for broad attack surface exposure to any remote user capable of reaching the target WordPress instance.\nOrganizations relying on SiteGround Security should prioritize immediate updates to the latest available version to mitigate the risk of exploitation and unauthorized security control bypass.",
  "technicalDetails": "The vulnerability exists due to improper handling of security checks within the SiteGround Security plugin logic, allowing an unauthenticated attacker to bypass intended restrictions.\nAt its core, the issue stems from an inadequate implementation of authorization or verification logic for certain plugin functionalities. The plugin fails to correctly validate the authentication status of requests, or improperly relies on client-side or easily spoofable parameters to determine authorized access.\nThe attack flow begins with the threat actor identifying the endpoint or functionality protected by the SiteGround Security plugin that lacks sufficient server-side authentication enforcement. By crafting a specific HTTP request, an attacker can bypass the intended access control mechanisms.\nBecause the plugin is intended to provide enhanced security for the WordPress site, the bypass effectively nullifies the protections provided by the affected component. This can potentially allow an attacker to interact with restricted features, alter configurations, or bypass other site-wide security measures enforced by the plugin.\nThe vulnerability affects SiteGround Security versions 1.6.6 and earlier. It is categorized as an authentication bypass or authorization bypass issue.\nExploitation is feasible over a network via standard HTTP/HTTPS requests. No interaction with an authenticated administrator or user is required, as the vulnerability is explicitly triggered in an unauthenticated context.\nUpon successful bypass, the impact depends on the specific security function being circumvented. If the bypass affects core hardening features, such as login protection, firewalls, or activity logging, the attacker gains the ability to operate under the radar or perform actions that would normally be blocked by the plugin. This significantly degrades the overall security posture of the WordPress installation and may be a precursor to further exploitation, such as unauthorized administrative actions or data exposure, depending on the capabilities of the specific component bypassed."
}