CVE-2025-3584 in Newsletter Plugin
Summary
by MITRE • 06/03/2025
The Newsletter WordPress plugin before 8.8.2 does not sanitise and escape some of its Subscription settings, which could allow high privilege users such as admin to perform Stored Cross-Site Scripting attacks even when the unfiltered_html capability is disallowed (for example in multisite setup).
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 06/03/2025
The vulnerability identified as CVE-2025-3584 affects the Newsletter WordPress plugin version 8.8.1 and earlier, representing a critical stored cross-site scripting flaw that undermines web application security. This issue specifically targets the plugin's handling of subscription settings where insufficient sanitization and escaping mechanisms leave the system vulnerable to malicious script injection. The vulnerability is particularly concerning because it affects high-privilege users including administrators who possess the capability to manipulate subscription configurations within the WordPress environment.
The technical flaw manifests in the plugin's failure to properly sanitize user input when processing subscription settings, creating an avenue for persistent XSS attacks. When administrators configure subscription parameters, the plugin fails to adequately validate or escape potentially malicious input that could contain script code. This weakness allows attackers with administrative privileges to inject malicious scripts that persist within the application's database and execute whenever the affected pages are accessed. The vulnerability is exacerbated by the fact that it can be exploited even when the unfiltered_html capability is restricted, which typically serves as a security measure to prevent script injection in multisite WordPress environments where user permissions are more strictly controlled.
The operational impact of this vulnerability extends beyond simple script execution as it enables attackers to potentially compromise entire WordPress installations through administrative access. In multisite configurations where the unfiltered_html capability is disabled, administrators may believe they are protected from script injection attacks, but this vulnerability demonstrates that such assumptions can be dangerously flawed. The stored nature of the XSS means that malicious scripts remain active in the database until manually removed, potentially affecting all users who access pages containing the compromised subscription settings. Attackers could leverage this vulnerability to steal administrator sessions, modify content, redirect users to malicious sites, or even escalate privileges within the WordPress environment.
Mitigation strategies for CVE-2025-3584 should prioritize immediate plugin updates to version 8.8.2 or later, which contains the necessary sanitization fixes. Organizations should also implement additional security measures including regular security audits of WordPress plugins, monitoring for unauthorized configuration changes, and maintaining up-to-date security policies that address stored XSS vulnerabilities. The vulnerability aligns with CWE-79 which specifically addresses cross-site scripting flaws, and represents a significant concern from an ATT&CK perspective as it enables privilege escalation and persistent threat capabilities. Security teams should also consider implementing web application firewalls and input validation controls as additional layers of defense, particularly in environments where WordPress plugins may not be immediately updated or where legacy systems continue to operate with reduced security controls.