CVE-2026-97723 in ka9q_ubersdr
Summary
by MITRE • 09/25/2026
madpsy ka9q_ubersdr before 0.1.58 has a stored cross-site scripting (XSS) vulnerability in the chat message rendering functionality. User-controlled URLs in chat messages were insufficiently neutralized before being converted into HTML links. Quotation characters could break out of the generated href attribute and introduce attacker-controlled HTML attributes, allowing arbitrary JavaScript to execute in the browser of another user when the stored chat message was rendered. No click on the malicious link was required.
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Analysis
by VulDB Data Team • 09/25/2026
The vulnerability identified in madpsy ka9q_ubersdr prior to version 0.1.58 represents a critical security flaw within its chat messaging subsystem, specifically categorized as a Stored Cross-Site Scripting (XSS) attack vector. This type of vulnerability is formally recognized under the Common Weakness Enumeration standard as CWE-79, which describes improper neutralization of input during web page generation. The core technical failure lies in the application's handling of user-supplied data within chat messages. When a user submits a message containing a URL, the system attempts to automatically convert this text into an HTML hyperlink for display purposes. However, the sanitization logic applied before rendering is insufficiently robust, failing to properly escape or validate special characters that are significant in HTML attribute contexts.
The operational mechanism of this exploit relies on the attacker injecting malicious payloads disguised as URLs within a chat message. Because the vulnerability allows quotation characters to break out of the generated href attribute, an attacker can construct input such as "http://example.com" onclick="alert(1)". When another user views this stored message, the browser parses the HTML and interprets the injected attributes rather than treating them as literal text. This results in the execution of arbitrary JavaScript code within the context of the victim's session. The severity of this flaw is significantly amplified by its persistent nature; since the malicious content is stored on the server side, it affects every user who views the compromised message without requiring any specific trigger from the victim beyond viewing the chat history.
This incident aligns with several tactics and techniques defined in the MITRE ATT&CK framework for enterprise security. The initial injection of the payload corresponds to T1059, specifically Command and Scripting Interpreter: JavaScript, as it involves executing script code within a web browser environment. Furthermore, because the attack does not require user interaction such as clicking a link or opening an attachment, it falls under the category of passive exploitation where the mere rendering of content triggers the malicious behavior. This characteristic makes it particularly dangerous in collaborative environments where messages are frequently reviewed by multiple users, potentially leading to widespread compromise if the application is used for sensitive communications.
The impact of this vulnerability extends beyond simple script execution. An attacker with sufficient skill can leverage DOM-based manipulation or cookie theft techniques to hijack user sessions, steal authentication tokens, or perform actions on behalf of the victim within the application. This could lead to unauthorized access to private data, modification of other users' messages, or further propagation of malicious content if the application allows for message editing or forwarding. The lack of required interaction means that social engineering elements are minimized, increasing the likelihood of successful exploitation in real-world scenarios where trust is placed in the integrity of shared chat logs.
To mitigate this vulnerability, immediate action must be taken to upgrade madpsy ka9q_ubersdr to version 0.1.58 or later, which addresses these input validation deficiencies. In addition to patching, developers should implement strict output encoding and context-aware escaping for all user-supplied data before it is rendered in HTML attributes. Utilizing a Content Security Policy (CSP) can also serve as an effective defense-in-depth measure by restricting the sources from which scripts can be loaded or executed, thereby neutralizing many XSS attacks even if they bypass input filters. Regular security audits and static code analysis focused on CWE-79 patterns are recommended to ensure that similar flaws do not exist in other parts of the application's rendering engine.