CVE-2025-13357 is a vulnerability classified under CWE-1188, which concerns the initialization of a resource with insecure default settings. Specifically, in HashiCorp Vault’s Terraform Provider version 4.2.0, the LDAP authentication method incorrectly sets the deny_null_bind parameter to false by default. This parameter controls whether LDAP anonymous or unauthenticated binds are denied. When set to false, it allows such binds, which can lead to an authentication bypass if the LDAP server itself permits anonymous binds. This means an attacker could potentially authenticate without valid credentials, gaining unauthorized access to Vault-managed secrets or infrastructure configurations. The vulnerability has a CVSS 3.1 base score of 7.4, indicating high severity, with the vector AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N. This means the attack can be performed remotely without privileges or user interaction but requires high attack complexity, likely due to needing specific LDAP server conditions. The vulnerability affects Vault Terraform Provider version 4.2.0 and is resolved in version 5.5.0. No known exploits are currently reported in the wild. The issue highlights the risk of insecure default configurations in security-critical tooling, emphasizing the need for secure defaults and proper configuration validation. Organizations relying on HashiCorp Vault with LDAP authentication should verify their deny_null_bind settings and upgrade to the patched version to mitigate risk.

For European organizations, this vulnerability poses a significant risk to the confidentiality and integrity of sensitive data managed through HashiCorp Vault, especially in environments where LDAP servers allow anonymous binds. Unauthorized access could lead to exposure of secrets, credentials, and infrastructure configurations, potentially enabling further lateral movement or data breaches. Given the widespread adoption of HashiCorp Vault and Terraform in cloud and DevOps environments across Europe, the impact could affect sectors such as finance, healthcare, government, and critical infrastructure. The vulnerability does not affect availability directly but compromises trust in authentication mechanisms. Organizations with complex LDAP setups or legacy configurations are particularly vulnerable. The risk is elevated in multi-tenant or hybrid cloud environments where Vault is used to manage secrets across diverse systems. Failure to patch or audit LDAP bind settings could result in compliance violations under GDPR and other data protection regulations due to unauthorized data access.

1. Immediately upgrade the Vault Terraform Provider to version 5.5.0 or later, where the deny_null_bind parameter default is securely set. 2. Audit all LDAP authentication configurations in Vault to ensure deny_null_bind is explicitly set to true, preventing anonymous binds. 3. Review and harden LDAP server configurations to disallow anonymous or unauthenticated binds at the directory level. 4. Implement monitoring and alerting for unusual authentication patterns or anonymous bind attempts in LDAP logs. 5. Conduct penetration testing and configuration reviews focusing on LDAP authentication flows within Vault environments. 6. Educate DevOps and security teams about the risks of insecure defaults and enforce secure configuration baselines for infrastructure-as-code tools. 7. Integrate configuration management tools to enforce deny_null_bind=true in Terraform scripts and Vault policies. 8. Consider network segmentation and access controls to limit exposure of LDAP and Vault services to trusted networks only. 9. Maintain up-to-date inventories of Vault provider versions deployed across environments to ensure timely patching.