CVE-2026-23843 identifies an authorization bypass vulnerability categorized under CWE-639 (Authorization Bypass Through User-Controlled Key) in the sibercii6-crypto project's PHP application teklifolustur_app. This application facilitates the creation, management, and tracking of client quotes. The vulnerability exists in versions prior to commit dd082a134a225b8dcd401b6224eead4fb183ea1c, where the offer view functionality improperly validates user permissions. Specifically, authenticated users can manipulate the 'offer_id' parameter in HTTP requests to access offers that do not belong to them. The root cause is the absence of proper authorization checks ensuring that the requested offer is owned by the currently authenticated user. This flaw allows unauthorized disclosure of potentially sensitive business information, such as client quotes and pricing details. The vulnerability does not require user interaction but does require the attacker to be authenticated, which limits exposure to some extent. The CVSS v3.1 score of 7.1 reflects a high severity, driven by network attack vector, low attack complexity, required privileges, and high confidentiality impact with limited integrity impact and no availability impact. The patch commit dd082a134a225b8dcd401b6224eead4fb183ea1c addresses this by implementing proper authorization checks to validate offer ownership before data access is granted. No known exploits have been reported in the wild, but the vulnerability poses a significant risk to confidentiality if exploited.

For European organizations using teklifolustur_app, this vulnerability could lead to unauthorized access to sensitive client quote data, potentially exposing confidential pricing strategies, client identities, and contract terms. This leakage can undermine client trust, damage business reputation, and lead to competitive disadvantages. Industries such as finance, manufacturing, and professional services that rely on accurate and confidential quote management are particularly vulnerable. The breach of confidentiality could also have regulatory implications under GDPR, as unauthorized access to client-related data may constitute a personal data breach. While the vulnerability does not affect system integrity or availability, the exposure of sensitive business information can have severe operational and financial consequences. Since exploitation requires authentication, insider threats or compromised user credentials increase risk. European organizations with remote access to the application over the internet face higher exposure due to the network attack vector.

Organizations should immediately apply the patch introduced in commit dd082a134a225b8dcd401b6224eead4fb183ea1c to ensure proper authorization checks are enforced. In addition to patching, conduct a thorough audit of access control mechanisms across the application to verify that all sensitive resources are protected by ownership validation. Implement strict role-based access controls (RBAC) and least privilege principles to minimize the risk from compromised accounts. Monitor application logs for unusual access patterns, such as users accessing multiple offers not belonging to them, which could indicate exploitation attempts. Employ multi-factor authentication (MFA) to reduce the risk of credential compromise. If feasible, segment the application environment to limit lateral movement in case of a breach. Educate users about the importance of safeguarding their credentials and recognizing suspicious activity. Finally, review data retention policies to minimize stored sensitive data exposure and ensure compliance with GDPR requirements.