CVE-2024-12139 in API Manager
Summary
by MITRE • 11/02/2026
The error handling implementation fails to properly sanitize or validate user-supplied input within URL parameters under specific conditions. This allows end-users to manipulate the error messages that are displayed by the application.
By exploiting this vulnerability, malicious actors can inject arbitrary content into error messages. This enables them to perform social engineering attacks, such as phishing or credential theft, by replacing legitimate error messages with malicious content, misleading users into compromising sensitive information or taking harmful actions.
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Analysis
by VulDB Data Team • 11/02/2026
The identified vulnerability stems from a fundamental flaw in the application's input validation and output encoding mechanisms, specifically within the module responsible for handling URL parameters during error reporting sequences. This defect classifies as an Unrestricted Upload of File with Dangerous Type or more accurately in this context, Improper Neutralization of Input During Web Page Generation (CWE-79), often referred to as Cross-Site Scripting when executed via browser rendering, but here it manifests primarily through the manipulation of server-generated error messages. The core technical issue lies in the failure to sanitize user-supplied data before it is embedded into dynamic content structures that are subsequently displayed to end-users. When a specific condition triggers an application-level error, such as a database query failure or authentication timeout, the system constructs an error message string by concatenating static text with variable input derived from URL parameters without applying appropriate encoding rules. This lack of neutralization allows special characters and script payloads to pass through the validation layer intact, effectively bypassing security controls that are typically designed to filter malicious content before it reaches the presentation tier.
The operational impact of this vulnerability extends beyond simple data leakage or application instability; it introduces a significant risk vector for social engineering attacks. By injecting arbitrary content into error messages, an attacker can craft deceptive notifications that mimic legitimate system alerts from trusted domains or services. For instance, if a user encounters a login failure, the manipulated error message could display text urging them to click a link to verify their account due to suspicious activity, complete with a URL pointing to a phishing site controlled by the adversary. This technique leverages the inherent trust users place in application-generated feedback mechanisms. The attacker does not need direct access to user credentials or internal systems; instead, they exploit the psychological tendency of users to follow instructions presented as official system communications. Consequently, this can lead to credential theft, malware installation via drive-by downloads linked from the injected content, or unauthorized account takeovers if multi-factor authentication bypasses are also included in the malicious payload.
From a threat intelligence perspective, this vulnerability aligns with several tactics within the MITRE ATT&CK framework. The initial exploitation phase corresponds to Initial Access through Spearphishing Attachment or Link, where the manipulated error message serves as the lure. If the injected content includes executable scripts that run upon viewing the page without further user interaction beyond loading it, it may also fall under Execution via Browser Rendering. Furthermore, if the vulnerability allows for session hijacking by stealing cookies stored in local storage through script injection, it would map to Credential Access and Collection techniques such as Steal Web Session Cookie. The persistence of this risk is high because error messages are often viewed during moments of user frustration or urgency, reducing the likelihood that a victim will critically evaluate the authenticity of the message before acting on its instructions.
Mitigation strategies must focus on implementing robust input validation and output encoding practices across all layers of the application stack. At the input layer, strict allow-listing should be applied to URL parameters, ensuring that only expected character sets and formats are accepted, with immediate rejection or sanitization of any deviations. However, defense in depth requires that even validated inputs must not be trusted implicitly during rendering. The output encoding mechanism must be context-aware, applying HTML entity encoding for data inserted into HTML bodies, JavaScript escaping for script contexts, and URL encoding for query string parameters. Additionally, implementing a Content Security Policy (CSP) header can significantly reduce the impact of any successful injection by restricting the sources from which scripts can be loaded or executed. Regular security testing, including dynamic application security scanning and manual penetration tests focused on error handling paths, is essential to identify similar flaws in other parts of the codebase that may share this architectural weakness.