CVE-2026-109893 in Presto Player Plugin
Summary
by MITRE • 10/15/2026
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in Brainstorm Force Presto Player presto-player allows Stored XSS.This issue affects Presto Player: from n/a through 4.5.3.
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Analysis
by VulDB Data Team • 10/15/2026
The identified vulnerability represents a classic instance of Improper Neutralization of Input During Web Page Generation, commonly known as Cross-Site Scripting or XSS. Specifically, this is classified as a Stored XSS flaw within the Presto Player plugin for WordPress, developed by Brainstorm Force. Unlike reflected XSS attacks where malicious scripts are executed immediately from a URL parameter, stored vulnerabilities involve the persistence of malicious payloads on the target server. In this context, an attacker can inject executable JavaScript code into fields or inputs that are subsequently saved to the database and rendered in web pages viewed by other users. This distinction is critical because it transforms the attack vector from a single-user interaction into a persistent threat capable of affecting multiple victims without further action from the initial attacker once the payload is stored.
The technical root cause lies in the insufficient sanitization or validation of user-supplied input before it is processed and displayed by the application. When users interact with Presto Player, particularly through features that allow for custom configurations, metadata entry, or potentially embedded content settings, the system fails to properly neutralize special characters such as angle brackets, quotes, and ampersands. Consequently, when these inputs are retrieved from storage and rendered in a browser context, they are interpreted not as plain text but as executable code by the client-side JavaScript engine. This failure adheres closely to CWE-79, which defines Cross-site Scripting (XSS) flaws where web applications include untrusted data in their output without validating or encoding it properly. The vulnerability affects versions of Presto Player ranging from no specific lower bound through version 4.5.3, indicating a long-standing issue that persisted across multiple releases until the patch was applied.
The operational impact of this stored XSS vulnerability is severe due to its potential for widespread exploitation and high persistence. An attacker who successfully injects a payload can execute arbitrary JavaScript in the context of any user viewing the affected page. This capability allows for session hijacking, where the attacker steals authentication cookies or tokens to impersonate legitimate users, including administrators. It also enables keylogging, credential harvesting through fake login forms injected into the DOM, and defacement of the website content. Furthermore, because the payload is stored on the server, it can be used in phishing campaigns by redirecting victims to malicious sites that mimic trusted domains. The attack aligns with MITRE ATT&CK technique T1059.007, which covers JavaScript execution, and potentially T1204.002 for Malicious File Execution if the script downloads additional payloads.
Mitigation strategies must address both immediate remediation and long-term defensive posture. The primary and most effective mitigation is to upgrade Presto Player to a version later than 4.5.3, where Brainstorm Force has implemented proper input validation and output encoding mechanisms. For organizations unable to patch immediately due to compatibility concerns, implementing a Web Application Firewall (WAF) can provide an additional layer of defense by filtering out requests containing known XSS patterns before they reach the application logic. Additionally, developers should enforce Content Security Policy headers that restrict the execution of inline scripts, thereby neutralizing many stored XSS payloads even if they are successfully injected into the database. Regular security audits and code reviews focusing on data flow from input to output are essential to prevent similar vulnerabilities in future updates or related plugins within the WordPress ecosystem.