CVE-2026-30840 in Wallos
Summary
by MITRE • 03/07/2026
Wallos is an open-source, self-hostable personal subscription tracker. Prior to version 4.6.2, there is a server-side request forgery vulnerability in notification testers. This issue has been patched in version 4.6.2.
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Analysis
by VulDB Data Team • 03/12/2026
The vulnerability identified as CVE-2026-30840 affects Wallos, an open-source personal subscription tracking application designed for self-hosted environments. This application enables users to monitor their subscription expenses and manage financial commitments through a web-based interface. The specific weakness resides within the notification testing functionality of the system, which allows unauthorized remote attackers to manipulate server-side requests through crafted inputs. The vulnerability represents a critical security flaw that could potentially enable attackers to access internal resources or perform unauthorized operations on the underlying infrastructure.
The technical implementation of this server-side request forgery vulnerability stems from inadequate input validation and sanitization within the notification tester component. When users attempt to test notification configurations, the application processes user-provided URLs or endpoints without proper validation mechanisms. This flaw permits attackers to inject malicious URLs that the server will subsequently attempt to access, effectively enabling them to make arbitrary requests from the server to internal or external systems. The vulnerability falls under the category of CWE-918, which specifically addresses server-side request forgery conditions where applications fail to properly validate user-supplied URLs or endpoints.
The operational impact of this vulnerability extends beyond simple data exposure, as it could potentially allow attackers to escalate privileges or access sensitive internal network resources. An attacker could leverage this weakness to target internal services that are not directly exposed to the internet, or to perform reconnaissance activities by making requests to internal systems that would normally be restricted. The self-hosted nature of Wallos means that organizations may have limited network segmentation, potentially increasing the attack surface and making internal resource access more feasible. This vulnerability directly maps to ATT&CK technique T1190, which describes server-side request forgery as a method for bypassing access controls and accessing internal systems.
Mitigation strategies for CVE-2026-30840 require immediate deployment of the patched version 4.6.2, which addresses the input validation issues in the notification testing functionality. Organizations should also implement additional defensive measures including network segmentation to limit access to internal resources, implementing proper URL validation and sanitization throughout the application, and monitoring for suspicious request patterns. Security teams should conduct thorough penetration testing to ensure no other similar vulnerabilities exist within the application's codebase, particularly in other components that handle user-provided URLs or endpoints. The vulnerability highlights the importance of validating all user inputs in web applications and demonstrates how seemingly minor functionality like notification testing can represent significant security risks when not properly secured. Regular security updates and vulnerability assessments should be implemented as part of the operational security posture to prevent similar issues from arising in the future.