CVE-2026-103905 in JTL-Shop
Summary
by MITRE • 10/15/2026
The authentication middleware of the JTL-Shop administration backend processes the plugin safe mode toggle on the admin logout route before checking whether the requesting user is authenticated. An unauthenticated remote attacker can therefore switch the shop's plugin safe mode on and off, which deactivates all installed plugins and their functionality, such as payment and shipping integrations, resulting in a shop-wide denial of service. The attack requires a single request and can be automated against many installations.
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Analysis
by VulDB Data Team • 10/15/2026
The vulnerability identified involves a critical authentication bypass within the JTL-Shop administration backend, specifically affecting the middleware responsible for handling plugin safe mode toggles during user logout operations. This flaw stems from an improper sequence of security checks where the system processes state-changing actions related to plugin configurations before verifying the identity and authorization status of the requesting entity. By failing to enforce authentication prior to executing administrative logic, the application allows unauthenticated remote attackers to interact with sensitive configuration endpoints that should be strictly protected behind a valid session or login credential check. This architectural oversight represents a fundamental failure in access control mechanisms, allowing external actors to manipulate core system settings without any form of verification.
From a technical perspective, this issue is classified under CWE-287, which denotes Improper Authentication, and aligns with MITRE ATT&CK technique T1078, Valid Accounts, although in this specific case, the attacker operates entirely without valid credentials by exploiting the logic gap before authentication occurs. The middleware processes the request to toggle the plugin safe mode on or off as part of the logout route handling but neglects to validate that the user initiating this action is actually logged into an administrative account. Consequently, any remote actor can send a crafted HTTP request to trigger this state change. This bypass effectively neutralizes one of the primary defenses against unauthorized configuration changes, turning what should be an authenticated administrative function into a publicly accessible operation.
The operational impact of this vulnerability is severe and results in a complete denial of service for e-commerce operations relying on JTL-Shop. When the plugin safe mode is activated by an attacker, it forcibly deactivates all installed plugins within the shop environment. This includes critical integrations such as payment gateways, shipping providers, inventory management systems, and other essential business logic extensions. The immediate consequence is that customers are unable to complete purchases because standard checkout processes rely on these deactivated modules. Furthermore, administrative functions dependent on specific plugins may also become inaccessible or malfunctioning, effectively paralyzing the entire shop's functionality until an administrator manually intervenes to restore normal operations.
This attack vector is particularly dangerous due to its simplicity and scalability. An unauthenticated attacker requires only a single HTTP request to execute the exploit, making it highly automatable across multiple installations using standard vulnerability scanning tools or custom scripts. The lack of rate limiting or additional security controls on this specific endpoint means that an attacker can rapidly target numerous vulnerable instances in a short timeframe. This ease of exploitation increases the likelihood of widespread compromise and sustained disruption for businesses dependent on the platform, leading to significant financial loss and reputational damage due to prolonged service unavailability.
To mitigate this vulnerability, immediate remediation should focus on enforcing strict authentication checks before any administrative state changes are processed within the middleware layer. Developers must ensure that all endpoints modifying critical system configurations, including plugin management settings, require a valid authenticated session with appropriate privileges prior to execution. Implementing robust access control lists and validating user sessions at the earliest possible stage of request processing will prevent unauthenticated actors from interacting with these sensitive functions. Additionally, applying vendor-provided security patches as soon as they become available is essential for restoring secure operation. Organizations should also consider implementing web application firewalls that can detect and block anomalous requests targeting administrative routes without proper authentication headers or session tokens.