CVE-2023-5798 is a high-severity Server-Side Request Forgery (SSRF) vulnerability identified in the Assistant WordPress plugin versions prior to 1.4.4. The vulnerability arises because the plugin fails to properly validate a user-controllable parameter before using it in the wp_remote_get() function, which is a WordPress HTTP API call to fetch remote resources. This lack of validation allows an authenticated user with at least Editor privileges to craft malicious requests that the server will execute internally. SSRF vulnerabilities enable attackers to make the server perform unintended HTTP requests, potentially accessing internal or protected resources that are not directly accessible from the outside. The vulnerability's CVSS v3.1 score is 8.8, reflecting its high impact on confidentiality, integrity, and availability. The attack vector is network-based with low attack complexity, requiring privileges equivalent to an Editor role but no user interaction. Exploitation could lead to unauthorized internal network scanning, data exfiltration, or further pivoting attacks within the hosting environment. Although no public exploits are currently known in the wild, the vulnerability is critical due to the common use of the Assistant plugin in WordPress environments and the relatively low privilege required to exploit it. The plugin’s failure to sanitize or restrict the URL parameter used in wp_remote_get() is the core technical flaw, making it possible to direct requests to arbitrary internal or external endpoints, potentially bypassing firewall rules or network segmentation. This SSRF can be leveraged to access sensitive internal services, metadata endpoints, or other internal APIs that are not intended to be exposed externally. Given WordPress’s widespread use, this vulnerability poses a significant risk to websites using the Assistant plugin, especially those with multiple users having Editor-level access.

For European organizations, the impact of CVE-2023-5798 can be substantial. Many European enterprises and public sector entities rely on WordPress for their web presence, including governmental, educational, and commercial websites. An SSRF vulnerability exploitable by users with Editor privileges could allow attackers to bypass perimeter defenses and access internal network resources, potentially leading to data breaches, unauthorized access to internal APIs, or disruption of services. Confidentiality could be compromised if sensitive internal endpoints or metadata services are accessed. Integrity and availability could be affected if the SSRF is used to trigger destructive actions or denial-of-service conditions on internal systems. The risk is amplified in multi-tenant hosting environments or where internal services hold critical business or personal data. Additionally, compliance with GDPR and other European data protection regulations could be jeopardized if personal data is exposed or exfiltrated due to this vulnerability. The vulnerability’s exploitation could also facilitate lateral movement within networks, increasing the scope and severity of attacks. Organizations with Editor-level users who are not fully trusted or who may be compromised face a higher risk. The lack of known exploits in the wild currently provides a window for proactive mitigation before widespread attacks occur.

To mitigate CVE-2023-5798, European organizations should take the following specific actions beyond generic patching advice: 1) Immediately update the Assistant WordPress plugin to version 1.4.4 or later, where the vulnerability is fixed. 2) Audit user roles and permissions within WordPress to ensure that only trusted users have Editor or higher privileges; consider restricting Editor roles or implementing stricter role separation. 3) Implement Web Application Firewall (WAF) rules to detect and block suspicious wp_remote_get() requests or unusual URL parameters that could indicate SSRF attempts. 4) Employ network segmentation and internal firewall rules to restrict the WordPress server’s ability to make arbitrary outbound HTTP requests, especially to internal IP ranges or sensitive metadata endpoints (e.g., cloud provider metadata services). 5) Monitor logs for unusual outbound HTTP requests initiated by WordPress processes, focusing on requests to internal or unexpected destinations. 6) Conduct regular security assessments and penetration tests targeting SSRF vectors in WordPress plugins. 7) Educate site administrators and content editors about the risks associated with plugin vulnerabilities and the importance of role-based access control. 8) Consider deploying runtime application self-protection (RASP) solutions that can detect and block SSRF attempts dynamically. These measures collectively reduce the attack surface and limit the potential impact of exploitation.