CVE-2026-94061 in Whistle Plugin
Summary
by MITRE • 10/09/2026
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in Designthemes Whistle - Sports Club whistle-sports-club allows Reflected XSS.This issue affects Whistle - Sports Club: from n/a through 4.2.
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Analysis
by VulDB Data Team • 10/09/2026
The identified security flaw represents a classic instance of Improper Neutralization of Input During Web Page Generation, commonly known as Cross-site Scripting or XSS. Specifically, this vulnerability manifests as a Reflected XSS within the Designthemes Whistle - Sports Club application, affecting versions ranging from n/a through 4.2. In a reflected XSS scenario, malicious script code is embedded directly into HTTP requests and then immediately returned by the web server to the user's browser without proper sanitization or encoding. This mechanism differs significantly from stored XSS, where payloads are saved in target servers, because here the attack relies heavily on social engineering tactics such as phishing links that trick users into executing the malicious script within their own session context.
From a technical perspective, the root cause lies in the application's failure to validate and sanitize user-supplied input before incorporating it into dynamically generated web pages. When a request containing specially crafted parameters reaches the server, the backend processes these inputs and reflects them back in the response body without applying necessary output encoding rules. This allows an attacker to inject executable JavaScript code that runs with the privileges of the victim's session. The vulnerability typically arises when developers assume input is safe or fail to implement robust filtering mechanisms against script tags, event handlers, or other HTML injection vectors.
The operational impact of this vulnerability can be severe depending on the sensitivity of the data accessible within the targeted application environment. An attacker who successfully exploits this flaw can execute arbitrary scripts in the context of the victim's browser session. This capability enables a range of malicious activities including stealing sensitive cookies and authentication tokens, performing actions on behalf of the user such as changing passwords or making transactions, defacing the website interface to damage reputation, and redirecting users to phishing sites designed to harvest credentials further. Since Whistle is used for sports club management, potential exposure could include personal data of members, financial information related to memberships, or administrative controls if an administrator falls victim to the attack vector.
This vulnerability aligns with CWE-79, which defines Improper Neutralization of Input During Web Page Generation as a category where web pages are generated using user input without adequate validation. Furthermore, in terms of tactical classification under the MITRE ATT&CK framework, this activity corresponds to T1059 Command and Scripting Interpretation, specifically JavaScript execution within a browser environment. It also facilitates T1534 Internal Spearphishing if used as part of a broader campaign targeting specific organizational members or staff through deceptive links.
To mitigate this risk, immediate remediation steps should focus on implementing strict input validation and output encoding strategies across all affected versions up to 4.2. Developers must ensure that any user-supplied data is validated against expected formats such as length, type, syntax, and range before processing. More critically, when rendering content back to the browser, developers must apply context-sensitive output encoding based on where the data appears in the HTML structure whether it be inside a script block, an attribute value, or plain text body. Utilizing established libraries that handle escaping automatically can significantly reduce human error. Additionally, deploying Content Security Policy headers can provide an additional layer of defense by restricting the sources from which scripts are allowed to load and execute, thereby limiting the impact even if some injection attempts succeed. Upgrading to a patched version released after 4.2 is also recommended as it likely contains these security fixes implemented at the framework level.