The Simple Banner plugin is a popular WordPress plugin used by website owners to display customizable banners at the top of their pages. With over 50,000 active installations, the plugin allows users to manage and configure banner content easily. While the plugin provides useful features, a critical vulnerability—CVE-2024-12769—was discovered during testing, which allows attackers to inject malicious JavaScript (JS) into the banner settings. This vulnerability enables attackers to execute stored XSS attacks, ultimately leading to the creation of a backdoor and account takeover by an attacker. This security flaw underscores the importance of input validation and sanitization, especially for plugins that manage dynamic content.
| CVE | CVE-2024-12769 |
| Plugin | Simple Banner < 3.0.4 |
| Critical | High |
| All Time | 1 412 345 |
| Active installations | 50 000+ |
| Publicly Published | March 11, 2025 |
| Last Updated | March 11, 2025 |
| Researcher | Dmitrii Ignatyev |
| OWASP TOP-10 | A7: Cross-Site Scripting (XSS) |
| PoC | Yes |
| Exploit | No |
| Reference | https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-12769 https://wpscan.com/vulnerability/02b5c1a8-cf2a-4378-bfda-84d841d88a18/ |
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Timeline
| November 7, 2024 | Plugin testing and vulnerability detection in the Simple Banner – Easily add multiple Banners/Bars/Notifications/Announcements to the top or bottom of your website have been completed |
| November 7, 2024 | I contacted the author of the plugin and provided a vulnerability PoC with a description and recommendations for fixing |
| March 11, 2025 | Registered CVE-2024-12769 |
Discovery of the Vulnerability
The vulnerability was discovered in the “Header Top Margin” field in the plugin’s main settings. This field is typically used to adjust the top margin of the banner, but it does not properly validate or sanitize user input. As a result, an attacker can inject JavaScript code into this field, which is then executed whenever the banner is rendered on a page. This vulnerability affects users with editor-level access or higher, allowing them to inject malicious scripts that will execute in the browser of any user who views the page containing the banner. The flaw was identified during a routine security audit of the plugin’s functionality and has significant implications for site security.
Understanding of XSS attack’s
Cross-Site Scripting (XSS) vulnerabilities occur when an attacker can inject malicious scripts into a web application, which are then executed in the browser of unsuspecting users. In WordPress, XSS vulnerabilities often arise from improper sanitization of user inputs, such as form fields or settings fields like those in the Simple Banner plugin. Real-world examples of XSS attacks in WordPress plugins include vulnerabilities found in WPForms and other form-related plugins, where attackers were able to inject scripts into form fields, leading to data theft or unauthorized access. In the case of CVE-2024-12769, the attacker can inject JavaScript into the “Header Top Margin” field, which could potentially hijack user sessions or escalate privileges.
Exploiting the XSS Vulnerability
To exploit CVE-2024-12769, an attacker with editor+ privileges:
POC:
Go to main settings of the plugin. Change "Header Top Margin" field in main settings to "Malicious JS code eval() and etc. For example 123" onmouseover=alert(1)// -> Save Settings (Admins and editors are allowed to use JS in posts/pages/comments/etc, so the unfiltered_html capability should be disallowed when testing for Stored XSS using such roles)____
The risks associated with CVE-2024-12769 are significant. In a real-world scenario, an attacker could exploit this vulnerability to escalate from a low-privileged user role (such as contributor or editor) to an administrator. Once the attacker gains admin privileges, they could take full control of the site, install malware, steal sensitive data, or deface the site. For instance, an attacker could inject a script that redirects users to a malicious site, installs keyloggers, or even alters the website’s content. This type of attack could go undetected for a long time, especially if the attacker is able to remain hidden behind the backdoor. This makes it especially dangerous for e-commerce websites, membership platforms, or any site that handles sensitive user information.
Recommendations for Improved Security
To mitigate the risks of CVE-2024-12769, users of the Simple Banner plugin should update to the latest patched version of the plugin as soon as it is available. Plugin developers should ensure that all user inputs, including the “Header Top Margin” field, are properly sanitized using WordPress’s esc_html() or wp_kses() functions, which prevent the execution of malicious scripts. Site administrators should restrict the ability to modify plugin settings to trusted users only and regularly audit plugins for security vulnerabilities. Furthermore, using a Web Application Firewall (WAF) and performing regular security scans can help detect and block such attacks before they are exploited. To prevent this type of attacks vendor used our methods of prevention.
By taking proactive measures to address Stored XSS vulnerabilities like CVE-2024-12769, WordPress website owners can enhance their security posture and safeguard against potential exploitation. Stay vigilant, stay secure.
#WordPressSecurity #StoredXSS #WebsiteSafety #StayProtected #HighVulnerability
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Dmitrii I.