CVE-2026-84028 in Bold Page Builder Plugin
Summary
by MITRE • 09/06/2026
The Bold Page Builder WordPress plugin before 5.9.9 does not sanitise and escape a shortcode attribute before outputting it in an HTML attribute, allowing users with the Contributor role and above to inject arbitrary web scripts that execute when a user views the affected page.
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Analysis
by VulDB Data Team • 09/06/2026
The vulnerability identified in the Bold Page Builder WordPress plugin prior to version 5.9.9 represents a classic instance of Cross-Site Scripting within an administrative context, specifically stemming from insufficient input validation and output encoding mechanisms. The core technical flaw lies in the handling of shortcode attributes where the application fails to properly sanitize user-supplied data before embedding it into HTML attribute values. This lack of escaping allows malicious actors to inject arbitrary JavaScript code directly into the page structure. Because this functionality is accessible to users with a Contributor role or higher, the attack surface includes any individual who can create or edit content within the WordPress environment, significantly expanding the potential for exploitation beyond just high-privilege administrators.
From an operational perspective, this vulnerability enables stored cross-site scripting attacks where malicious scripts are persisted on the server and executed whenever another user views the affected page. The impact is severe as it allows attackers to hijack administrative sessions by stealing cookies or authentication tokens, perform actions on behalf of victims such as creating new administrator accounts, defacing websites, or redirecting users to phishing sites. Since WordPress plugins often handle sensitive site configurations and content management tasks, compromising these roles can lead to full control over the web application infrastructure. The persistence of the payload means that every subsequent view by an authorized user potentially triggers the malicious script, amplifying the blast radius across all active sessions with elevated privileges.
This vulnerability aligns closely with Common Weakness Enumeration identifier CWE-79, which classifies improper neutralization of input during web page generation as a primary cause for cross-site scripting flaws. The failure to escape output in an HTML attribute context is a specific manifestation of this weakness where special characters are not converted into their corresponding HTML entities before rendering. Furthermore, the exploitation technique maps directly to MITRE ATT&CK tactic T1059, specifically sub-technique 007 for JavaScript execution, and falls under the initial access vector often associated with compromised credentials or insider threats given the required Contributor-level permissions. The attack chain typically involves crafting a malicious shortcode that includes script tags within an attribute value, which bypasses basic filtering due to the absence of context-aware output encoding.
Mitigation strategies must prioritize immediate upgrading to version 5.9.9 or later where these sanitization and escaping protocols have been corrected by the developers. For organizations unable to patch immediately, implementing a Web Application Firewall with rulesets designed to detect and block script injection in URL parameters and form submissions can provide temporary relief. Additionally, enforcing strict Content Security Policy headers that restrict inline script execution can significantly reduce the impact of successful exploitation attempts. It is also critical to review user roles within WordPress environments to ensure that only trusted individuals are assigned Contributor or higher privileges, thereby limiting the pool of potential attackers who could leverage this flaw for malicious purposes.