CVE-2026-63301 in Quick.CMS
Summary
by MITRE • 07/28/2026
In Quick.CMS, the administrative user interface restricts deletion of the primary language by omitting the corresponding option from the interface; however, the underlying language-deletion API endpoint does not enforce an equivalent server-side authorization check. As a result, an authenticated administrator can bypass the UI-level restriction and delete the primary language by sending a direct HTTP request to the API endpoint. Successful deletion of the primary language results in a Denial of Service (DoS) of application.
Critically, when combined with a separate Cross-Site Request Forgery (CSRF) vulnerability (CVE-2026-1468) an unauthenticated remote attacker can craft a malicious link, which if visited by an authenticated administrator, will trigger the DoS condition without direct access to the application
The vendor assessed the likelihood of exploitation as very low and determined that a fix is not necessary.
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Analysis
by VulDB Data Team • 07/28/2026
Quick.CMS contains a critical authorization flaw that enables authenticated administrators to bypass UI restrictions and delete the primary language through direct API calls, creating a denial of service condition. This vulnerability stems from a mismatch between client-side interface controls and server-side validation mechanisms, representing a classic case of insufficient authorization checks as classified under CWE-863. The administrative user interface intentionally omits the option to delete the primary language, yet the underlying API endpoint lacks proper server-side authorization enforcement to prevent this action. When an authenticated administrator sends a direct HTTP request to the language deletion endpoint, the system processes the request without verifying whether the operation should be permitted, effectively circumventing the intended UI-level restriction.
The operational impact of this vulnerability extends beyond simple authorization bypass to create a severe denial of service condition within the application. Deletion of the primary language fundamentally disrupts the CMS functionality, as all content becomes inaccessible due to missing language references and localization dependencies. This DoS condition affects all users of the system and requires administrative intervention to restore proper functionality. The vulnerability operates at the API layer where access controls fail to properly validate user permissions against critical operations, making it particularly dangerous because it allows privileged users to perform actions outside their intended scope.
When combined with a separate Cross-Site Request Forgery vulnerability (CVE-2026-1468), this authorization flaw becomes even more severe as it enables unauthenticated remote attackers to trigger the denial of service condition. An attacker can craft a malicious link that, when visited by an authenticated administrator, automatically executes the language deletion API call through CSRF exploitation. This combination transforms what might otherwise be a limited authorization issue into a remotely exploitable DoS vulnerability, aligning with ATT&CK technique T1213.002 for credential access and privilege escalation through API manipulation. The attacker does not require direct system access or authentication credentials beyond crafting the malicious link, making this attack vector particularly dangerous for application availability.
The vendor's assessment that exploitation likelihood is very low and that a fix is unnecessary represents a significant security oversight. This vulnerability demonstrates a fundamental flaw in the application's authorization model where UI restrictions are treated as sufficient security controls rather than merely user experience enhancements. The lack of proper server-side validation creates a persistent risk that can be exploited by both authenticated users with malicious intent and unauthenticated attackers through CSRF techniques. Security standards such as OWASP Top Ten A07:2021 and CWE-863 emphasize the critical importance of implementing robust server-side authorization controls to prevent privilege escalation and unauthorized operations, making this vulnerability particularly concerning given its potential for system-wide disruption.
The technical implementation flaw lies in the absence of proper access control validation at the API endpoint level, where the system should enforce business rules regardless of how requests are initiated. This represents a failure to implement defense-in-depth principles where multiple layers of security controls should be in place rather than relying on single points of validation. The vulnerability's persistence suggests that the application architecture lacks comprehensive authorization checks that should be enforced at all levels of operation, making it an attractive target for attackers seeking to disrupt service availability. Proper implementation would require server-side validation that prevents deletion of primary languages regardless of how the request is submitted, whether through direct API calls or CSRF attacks.