CVE-2026-44936
Summary
by MITRE • 07/06/2026
Missing filtering when the helmRepoURLRegex field isn't set on a GitRepo resource in SUSE Rancher Fleet's bundle reader in 0.15 before 0.15.2, 0.14 before 0.14.6, 0.13 before 0.13.11 and 0.12 before 0.12.15 forwards Helm authentication credentials (BasicAuth) to any URL specified in the helm.repo field of a fleet.yaml file, allowing attackers able to push to fleet monitored git repos to leak helm access credentials.
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Analysis
by VulDB Data Team • 07/06/2026
The vulnerability exists within SUSE Rancher Fleet's bundle reader component where insufficient input validation occurs when processing GitRepo resources that lack a defined helmRepoURLRegex field. This flaw represents a critical security oversight that directly violates the principle of least privilege and proper access control mechanisms. The absence of filtering allows unauthorized credential exposure when Helm repository URLs are processed through the fleet.yaml configuration files, creating an attack vector that can be exploited by malicious actors with write access to monitored git repositories.
This vulnerability stems from a lack of proper validation and sanitization of Helm repository URLs within the Fleet bundle reader functionality. When a GitRepo resource is processed without a helmRepoURLRegex field defined, the system fails to validate or filter the helm.repo URL values contained in fleet.yaml files. The technical implementation appears to blindly forward authentication credentials to any specified repository URL, regardless of its legitimacy or security posture. This behavior creates an information disclosure vulnerability where BasicAuth credentials can be leaked to unintended targets within the attack surface.
The operational impact of this vulnerability extends beyond simple credential leakage as it enables attackers with write permissions to monitored git repositories to potentially escalate their privileges and gain access to multiple Helm repositories across the fleet infrastructure. The flaw allows for arbitrary URL redirection of authentication tokens, which can result in unauthorized access to private Helm repositories that may contain sensitive applications or proprietary software components. This vulnerability directly impacts the integrity and confidentiality of containerized application deployments managed through Rancher Fleet.
Security practitioners should note this vulnerability aligns with CWE-20 (Improper Input Validation) and represents a clear violation of secure coding practices. The attack pattern follows typical privilege escalation techniques described in MITRE ATT&CK framework under T1566 (Phishing for Information) and T1078 (Valid Accounts). Organizations utilizing Rancher Fleet should immediately implement mitigations including mandatory helmRepoURLRegex field configuration, network segmentation to restrict access to Helm repositories, and comprehensive monitoring of git repository write activities. The recommended remediation involves upgrading to patched versions of Rancher Fleet where proper URL validation and credential filtering mechanisms have been implemented to prevent unauthorized credential forwarding.
The vulnerability demonstrates a fundamental flaw in the authentication handling mechanism that should have been addressed through defensive programming techniques including input sanitization, URL validation, and access control enforcement. Organizations must ensure that all external resource references within configuration files undergo proper validation before any authentication credentials are forwarded to remote endpoints. This particular issue highlights the importance of implementing robust security controls during the development lifecycle and conducting thorough security reviews of configuration management components that handle sensitive authentication data.