CVE-2025-28895 in Custom Top Bar Plugin
Summary
by MITRE • 03/12/2025
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in sumanbiswas013 Custom top bar allows Stored XSS. This issue affects Custom top bar: from n/a through 2.0.2.
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Analysis
by VulDB Data Team • 03/12/2025
This vulnerability represents a critical cross-site scripting flaw in the sumanbiswas013 Custom top bar plugin for WordPress, classified as CWE-79 Improper Neutralization of Input During Web Page Generation. The weakness allows attackers to inject malicious scripts into web pages that are then executed by other users, creating a persistent security risk through stored XSS attacks. The vulnerability exists within the plugin's handling of user input during web page generation processes, where insufficient sanitization or validation occurs before rendering content to end users. This specific issue affects all versions from the initial release through version 2.0.2, indicating a long-standing flaw that has not been properly addressed in the codebase.
The technical implementation of this vulnerability occurs when user-provided data enters the plugin's input processing pipeline without adequate sanitization measures. When administrators or users configure the custom top bar functionality, the plugin fails to properly escape or filter potentially malicious input before storing and subsequently rendering it in web pages. This creates an ideal environment for attackers to inject malicious JavaScript code that gets stored in the application's database or configuration files. The stored nature of this vulnerability means that once injected, the malicious script persists and executes automatically whenever affected pages are loaded by other users, making it particularly dangerous for content management systems where multiple users interact with the same interface.
The operational impact of this vulnerability extends beyond simple script execution, as it can enable attackers to perform a wide range of malicious activities including session hijacking, credential theft, data exfiltration, and privilege escalation within the affected WordPress environment. According to ATT&CK framework category T1566.001, this vulnerability represents a form of credential access through malicious input, while T1203 covers the exploitation of web application vulnerabilities for persistent access. The attack surface is particularly concerning given that WordPress plugins often have elevated privileges and access to sensitive user data, making successful exploitation potentially devastating for organizations relying on this platform. The vulnerability's presence across multiple versions suggests that the plugin development team has not adequately addressed input validation issues, leaving users exposed to ongoing risks.
Mitigation strategies for this vulnerability should include immediate patching of the Custom top bar plugin to version 2.0.3 or later if available, or implementing temporary workarounds such as input validation at the web server level using mod_security rules or similar filtering mechanisms. Organizations should also conduct comprehensive security audits of their WordPress installations to identify other potentially vulnerable plugins or themes that may exhibit similar input handling flaws. The implementation of Content Security Policy headers can provide additional defense-in-depth measures to prevent execution of unauthorized scripts even if the primary vulnerability is not fully patched. Security monitoring should be enhanced to detect suspicious input patterns and anomalous behavior in web application logs, as the stored nature of the vulnerability means that malicious payloads may remain dormant until triggered by legitimate user interactions with the affected plugin functionality.