CVE-2026-23843 identifies an authorization bypass vulnerability in the teklifolustur_app, a PHP-based web application designed for creating, managing, and tracking client quotes. The vulnerability is classified under CWE-639 (Authorization Bypass Through User-Controlled Key) and manifests as an Insecure Direct Object Reference (IDOR) in the offer view functionality. Specifically, authenticated users can manipulate the 'offer_id' parameter in HTTP requests to access offers that belong to other users without proper authorization checks. This occurs because the application fails to verify that the requested offer is owned by the currently authenticated user. The vulnerability affects all versions of the application prior to commit dd082a134a225b8dcd401b6224eead4fb183ea1c, where a patch was introduced to enforce proper authorization. The CVSS v3.1 base score is 7.1, reflecting a high severity due to the vulnerability's network attack vector, low attack complexity, requirement for privileges (authenticated user), no user interaction, unchanged scope, high confidentiality impact, low integrity impact, and no availability impact. While no known exploits have been reported in the wild, the vulnerability allows unauthorized disclosure of sensitive business data, potentially leading to information leakage and privacy violations. The flaw highlights the critical importance of implementing robust access control checks in web applications handling sensitive client data.

For European organizations, the primary impact of this vulnerability is the unauthorized disclosure of sensitive client and business offer information, which can lead to breaches of confidentiality and potential regulatory non-compliance, especially under GDPR. Exposure of such data can damage client trust, lead to competitive disadvantage, and possibly result in legal penalties. Since the vulnerability requires authentication, insider threats or compromised user accounts pose significant risks. The integrity and availability of the application are less impacted, but the confidentiality breach alone is critical for organizations handling sensitive commercial data. SMEs and enterprises using PHP-based CRM or quote management systems similar to teklifolustur_app are particularly at risk. The lack of known exploits in the wild suggests limited immediate threat, but the ease of exploitation and high confidentiality impact necessitate urgent remediation to prevent potential targeted attacks or insider misuse.

European organizations should immediately apply the patch introduced in commit dd082a134a225b8dcd401b6224eead4fb183ea1c to ensure proper authorization checks on the offer_id parameter. Beyond patching, organizations should conduct a thorough code review of all object references in the application to verify that access controls are consistently enforced. Implement role-based access controls (RBAC) and ensure that authorization logic is centralized and tested. Employ logging and monitoring to detect unusual access patterns or attempts to access unauthorized offers. Regularly audit user privileges and enforce the principle of least privilege to minimize risk from compromised accounts. Additionally, conduct security awareness training for users to recognize and report suspicious activity. For future development, adopt secure coding practices that include authorization checks as part of the development lifecycle and use automated security testing tools to detect IDOR vulnerabilities.