Horizon Alert
Summary of the vulnerability and why it matters
A critical vulnerability has been identified in the My Calendar plugin for WordPress, which could allow an unauthenticated attacker to gain administrative access to a WordPress site. This issue stems from how the plugin processes event data, potentially enabling unauthorized modification of user credentials. The main concern is confirming the relevance and exposure of this plugin within your digital assets.
- Allows unauthorized site control.
- Secures administrative access and user data.
- Assess plugin use for potential exposure.
Attack Path
How an attacker could exploit the issue
An unauthenticated attacker can exploit this vulnerability by leveraging a publicly accessible plugin page to inject malicious shortcode. This shortcode, when processed by the plugin, allows the attacker to execute arbitrary PHP functions, ultimately leading to the overwriting of administrator credentials and full control of the WordPress site.
- No authentication required.
- Triggered by crafted user input.
- Results in administrator account takeover.
Live Threat
Current exploitation, exposure, and threat context
An unauthenticated attacker could gain administrative access to a WordPress site by exploiting a flaw in the My Calendar plugin. This is possible when the plugin is configured to use its default publicly accessible page, allowing the attacker to inject malicious code that manipulates user credentials and grants them full control of the WordPress dashboard.
- WordPress administrator account credentials.
- Unsanitized GET parameter leads to code execution.
- Full administrative control of the website.
Operational Fix
Recommended remediation, mitigation, and detection steps
The My Calendar plugin's privilege escalation vulnerability impacts WordPress sites, likely placing ownership with the application or platform team responsible for managing WordPress instances. The immediate first step is to inventory all WordPress deployments, identify which ones use this plugin, and assess their exposure, particularly if the `/my-calendar/` page is publicly accessible or business-critical. This will help in identifying the accountable owner and prioritizing remediation efforts.
- WordPress application and platform teams own this.
- Verify all WordPress sites using the plugin.
- Plan remediation based on risk assessment.
