CVE-2026-88993 in All Bootstrap Blocks Plugin
Summary
by MITRE • 09/18/2026
The All Bootstrap Blocks WordPress plugin through 1.3.31 does not properly escape a block attribute before outputting it in HTML tag-name position, allowing users with Contributor-level access and above to inject arbitrary web scripts that execute when the affected content is viewed.
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Analysis
by VulDB Data Team • 09/18/2026
The vulnerability identified in All Bootstrap Blocks WordPress plugin versions through 1.3.31 represents a significant security flaw rooted in improper input validation and output encoding mechanisms. Specifically, the application fails to properly escape block attributes before rendering them within HTML tag-name positions. This technical deficiency allows for Cross-Site Scripting attacks, commonly referred to as reflected or stored XSS depending on how the data is persisted. The core issue lies in the plugin's handling of user-supplied input that is directly embedded into structural elements of the Document Object Model without adequate sanitization. When a block attribute containing malicious script code is processed by the server-side logic and subsequently rendered in the browser, the web application interprets this content as executable JavaScript rather than plain text data. This misinterpretation occurs because the output context requires specific encoding to neutralize special characters that have meaning in HTML markup, such as angle brackets or quotation marks, which are left unescaped due to the coding oversight.
From an operational perspective, this vulnerability poses a severe risk to both website administrators and end-users who interact with content generated by the affected plugin. The attack vector is particularly concerning because it requires only Contributor-level access or higher within the WordPress ecosystem. This relatively low privilege threshold means that individuals with limited administrative rights can still execute arbitrary web scripts on behalf of other users, including those with elevated privileges like Administrators. When a victim user views content containing the injected payload, their browser executes the malicious code in the context of the vulnerable site. This execution environment grants the attacker access to session cookies, authentication tokens, and potentially sensitive data stored locally by the browser. The consequences can range from defacement of the website interface to complete account takeover if administrative credentials are harvested or manipulated through script injection.
The classification of this vulnerability aligns with established industry standards for web application security flaws. It is categorized under CWE-79, which defines Improper Neutralization of Input During Web Page Generation known as Cross-site Scripting. The specific mechanism involves the failure to encode output in an HTML tag-name context, a nuance that distinguishes it from standard attribute-based XSS vectors but remains equally dangerous due to its ability to alter DOM structure and execute scripts. In terms of offensive security frameworks such as MITRE ATT&CK for Enterprise, this vulnerability facilitates techniques associated with Collection via Browser Redirects or Credential Access through Stealing Web Session Cookies. Attackers can leverage the executed script to perform actions that mimic legitimate user behavior, thereby bypassing traditional perimeter defenses that do not inspect client-side execution contexts.
Mitigation strategies must address both immediate remediation and long-term defensive posture improvements. The primary solution is for plugin developers to apply strict output encoding functions provided by the WordPress framework before rendering any user-supplied data in HTML tag-name positions. Functions such as esc_attr or custom sanitization routines that whitelist allowed characters should be implemented to ensure that only expected input formats are processed. For site administrators unable to immediately update the plugin, temporary mitigations include restricting contributor-level access to trusted individuals and implementing a Web Application Firewall capable of detecting and blocking XSS payloads in HTTP requests. Additionally, enabling Content Security Policy headers can help mitigate the impact by restricting the sources from which scripts can be loaded or executed, thereby reducing the effectiveness of injected code even if it bypasses input validation controls. Regular auditing of third-party plugins for similar encoding deficiencies is essential to maintain a robust security posture against evolving web-based threats.