CVE-2026-39600 in Aculect AI Companion Plugin
Summary
by MITRE • 10/02/2026
URL Redirection to Untrusted Site ('Open Redirect') vulnerability in Mehul Gohil Aculect AI Companion aculect-ai-companion allows Phishing.This issue affects Aculect AI Companion: from n/a through 0.8.1.
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Analysis
by VulDB Data Team • 10/02/2026
The identified vulnerability represents a classic Open Redirect flaw within the Aculect AI Companion application, specifically affecting versions ranging from an unspecified initial release up to version 0.8.1. This security defect stems from improper validation of user-supplied input used for URL redirection logic. When the application processes redirect requests, it fails to adequately verify whether the target destination is a trusted domain or allows arbitrary external URLs. Consequently, attackers can manipulate the redirect parameter to point towards maliciously crafted domains controlled by threat actors rather than legitimate internal resources or expected third-party services. This lack of strict allow-listing for redirection targets creates a significant security gap that undermines the integrity and trustworthiness of the application's navigation flow.
The operational impact of this vulnerability is primarily centered around facilitating phishing attacks against end-users. By exploiting the open redirect, an attacker can craft a deceptive URL that appears to originate from or lead directly through the legitimate Aculect AI Companion domain. This technique leverages the inherent trust users place in known and verified web addresses. When a user clicks on such a manipulated link, they are seamlessly redirected to a phishing site designed to mimic the look and feel of the authentic application or related services. The seamless transition from the trusted domain to the malicious destination often bypasses initial suspicion, as the browser's address bar may initially display the legitimate host before loading the external content. This significantly increases the success rate of social engineering campaigns aimed at harvesting credentials, personal identifiable information, or installing malware on victim devices.
From a technical classification perspective, this vulnerability aligns with CWE-601, which defines URL Redirection to Untrusted Site (Open Redirect). The flaw is characterized by the application's failure to perform sufficient validation checks before executing a redirect operation based on user input. In many modern web architectures and single-page applications, such redirects are common for handling authentication flows or external integrations. However, when these mechanisms lack robust sanitization of query parameters or path segments, they become potent vectors for abuse. The absence of strict domain verification allows the application to act as a trusted bridge to malicious infrastructure, effectively weaponizing its own reputation against its user base. This type of vulnerability is frequently exploited in conjunction with other attack chains where initial access is gained through deceptive links distributed via email or social media platforms.
The threat landscape associated with this flaw maps directly to several techniques within the MITRE ATT&CK framework. Specifically, it relates to T1566.002, which covers Spearphishing Link attacks under the broader category of Initial Access. Attackers utilize these links as the primary delivery mechanism for social engineering efforts. Furthermore, if the phishing site captures session cookies or tokens due to similar domain characteristics in subdomains, it may also relate to T1539, Steal Web Session Cookie, although this depends on specific implementation details not fully detailed here. The core objective remains Initial Access through deceptive redirections that exploit user trust and browser security models. Understanding these mappings helps organizations prioritize remediation efforts based on the potential for initial compromise of their environment.
Mitigation strategies must focus on implementing strict validation mechanisms at both the application logic level and potentially within reverse proxy configurations if applicable. The most effective defense is to maintain a whitelist of allowed redirect destinations, ensuring that only predefined internal paths or explicitly approved external domains can be targeted by redirection functions. If dynamic redirects are necessary, developers should implement rigorous input sanitization that rejects any URL containing suspicious characters, protocol deviations, or domain mismatches relative to the application's origin. Additionally, employing Content Security Policy headers with strict directives regarding frame-ancestors and script-src can help mitigate some downstream effects of phishing sites loaded via such redirects. Regular security testing, including automated scans for open redirect vulnerabilities during the development lifecycle, is essential to prevent regression of this issue in future releases beyond version 0.8.1.