CVE-2026-110290 in Top 10 Popular Posts Plugin
Summary
by MITRE • 10/16/2026
The WebberZone Top 10 — Popular Posts plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'other_attributes (parsed to inject instance_id) + undeclared is_widget' parameter in all versions up to, and including, 4.5.2 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. The exploit requires setting the undeclared is_widget flag to '1' via block JSON, which activates the vulnerable code path that concatenates the attacker-controlled instance_id value into an unescaped HTML class attribute.
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Analysis
by VulDB Data Team • 10/16/2026
The WebberZone Top 10 — Popular Posts plugin for WordPress contains a critical stored cross-site scripting vulnerability affecting all versions up to and including 4.5.2. This security flaw stems from insufficient input sanitization and inadequate output escaping within the plugin's handling of block configuration data. Specifically, the vulnerability resides in the processing of the other_attributes parameter, which is parsed to inject an instance_id value into the generated HTML structure. The exploit mechanism relies on manipulating a specific undeclared flag named is_widget by setting it to 1 via block JSON payload. When this condition is met, the plugin activates a vulnerable code path that concatenates the attacker-controlled instance_id directly into an unescaped HTML class attribute without proper validation or encoding procedures.
This architectural weakness allows authenticated attackers with contributor-level access and above to inject arbitrary web scripts into pages managed by the WordPress site. Because the vulnerability results in stored cross-site scripting, the malicious script is persisted within the database as part of the page content rather than being transiently passed via URL parameters. Consequently, every time a user accesses an affected page containing the injected payload, the browser will execute the malicious JavaScript code. This persistence significantly amplifies the potential impact compared to reflected XSS attacks, as it does not require complex social engineering tactics to trick users into clicking specific links; simply viewing the compromised content triggers the execution of the attacker's script.
The operational impact of this vulnerability is severe, particularly in environments where multiple user roles interact with site content. Contributors and higher-privileged users can leverage their access rights to embed malicious code that targets administrators or other visitors. The injected scripts can perform a variety of harmful actions depending on the context, including stealing session cookies, performing authenticated actions on behalf of victims, defacing web pages, or redirecting users to phishing sites. In many cases, such attacks facilitate account takeover scenarios where attackers hijack administrative sessions by exfiltrating authentication tokens stored in browser local storage or cookies.
From a classification perspective, this vulnerability aligns with CWE-79, which describes Improper Neutralization of Input During Web Page Generation commonly known as Cross-site Scripting. The specific mechanism involves the lack of proper encoding when outputting user-supplied data into HTML attributes, falling under subcategories such as CWE-80 and CWE-116 depending on the exact context of injection. In terms of adversary tactics, this exploit maps to MITRE ATT&CK technique T1059, Command and Scripting Interpreter, specifically JavaScript execution within a browser environment. It also relates to T1132, Data Encoding, as attackers may encode payloads to bypass basic filters before storage in the database.
Mitigation strategies should prioritize immediate patching of the WebberZone Top 10 — Popular Posts plugin to version 4.5.3 or later where these input validation and output escaping issues have been resolved by the vendor. Administrators must ensure that all plugins are kept up-to-date with security patches released by their respective developers. In addition to software updates, implementing a Web Application Firewall can provide an additional layer of defense by filtering out malicious payloads attempting to exploit known vulnerabilities in real-time. For organizations unable to patch immediately due to compatibility concerns, restricting contributor-level access and auditing user inputs for suspicious patterns such as JSON blocks containing undeclared flags may reduce the risk surface until a permanent fix is deployed. Regular security audits and code reviews focusing on input sanitization practices are essential preventive measures against similar vulnerabilities in WordPress ecosystems.