CVE-2026-54378 in VitaFit
Summary
by MITRE • 11/05/2026
VitaFit cloud API before 2026-10-30 contained a broken access control vulnerability that allows any authenticated user to obtain temporary AWS credentials by calling the POST /front/user/s3/token/ endpoint. Attackers can use these improperly scoped credentials to list the shared storage bucket and read or overwrite other users' stored files, enabling unauthorized cross-user data access and manipulation.
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Analysis
by VulDB Data Team • 11/05/2026
The vulnerability identified in VitaFit cloud API prior to version 2026-10-30 represents a critical failure in server-side access control mechanisms, specifically categorized under CWE-284 Improper Access Control. This flaw resides within the authentication and authorization logic governing the POST /front/user/s3/token/ endpoint. The core technical deficiency lies in the API's inability to properly validate whether the requesting user has permission to generate temporary AWS credentials for resources belonging to other users or shared organizational buckets. Instead of restricting token generation to only those S3 paths explicitly associated with the authenticated identity, the service accepts requests from any validly logged-in account and issues tokens that possess broader permissions than intended by the security architecture. This misconfiguration effectively bypasses the principle of least privilege, allowing a lower-privileged actor to escalate their access rights significantly within the cloud infrastructure environment.
From an operational perspective, this vulnerability enables severe unauthorized cross-user data access and manipulation. An attacker who has obtained valid credentials for any user account on the platform can invoke the vulnerable endpoint to retrieve temporary AWS Security Token Service (STS) credentials. These credentials are improperly scoped, granting permissions that extend beyond the individual user's private storage space into shared or public-facing S3 buckets managed by the application infrastructure. Consequently, adversaries can enumerate objects within these broader storage containers using standard AWS SDK operations such as ListObjectsV2. This capability facilitates the discovery of sensitive files belonging to other customers, including potentially personally identifiable information (PII), financial records, or proprietary business data stored in the cloud environment.
The impact extends beyond mere data exfiltration to include active data manipulation and integrity compromise. With write permissions granted through these improperly scoped temporary credentials, an attacker can overwrite existing objects within the shared storage bucket. This action could lead to the destruction of critical application assets, such as configuration files or media resources required for service operation. Furthermore, if specific file types are served directly from S3 with public read access policies that rely on signed URLs generated by this endpoint, attackers might replace legitimate content with malicious payloads, potentially leading to further exploitation chains involving client-side attacks against other users who download the compromised assets. The ability to both read and write arbitrary objects in a shared bucket constitutes a high-severity integrity violation alongside confidentiality breaches.
In terms of threat modeling and industry standards, this vulnerability aligns closely with MITRE ATT&CK technique T1530 Data from Cloud Storage Object or Bucket Enumeration for reconnaissance and data staging, as well as T1567 Exfiltration Over Web Service if the stolen data is transmitted externally. The exploitation path also reflects CWE-862 Missing Authorization, where the application fails to enforce access controls on API endpoints that perform sensitive actions involving shared resources. The scenario illustrates a common cloud-native security anti-pattern where backend services trust client-supplied context or fail to validate resource ownership at the server level before issuing privileged tokens. This type of flaw is particularly dangerous in multi-tenant SaaS environments because it allows lateral movement between tenant boundaries, undermining data isolation guarantees that are fundamental to secure cloud architecture design.
Mitigation strategies must focus on immediate remediation and long-term architectural improvements. The primary fix involves patching the VitaFit API to version 2026-10-30 or later, where the endpoint logic has been corrected to strictly validate resource ownership before generating AWS credentials. Developers should implement robust authorization checks that ensure the user requesting temporary tokens only receives permissions scoped exclusively to their own unique storage prefix or bucket partition. Additionally, implementing strict IAM policies for service roles used by the API can limit the scope of generated STS tokens using conditions such as aws:ResourceTag or specific ARN restrictions. Security teams should also audit existing S3 bucket policies to ensure they do not rely solely on application-level controls and instead enforce least-privilege access at the cloud provider level. Regular penetration testing focused on broken object level authorization (BOLA) patterns is recommended to detect similar flaws in other API endpoints before they can be exploited by malicious actors seeking to compromise multi-tenant data isolation.