CVE-2025-13357 is a vulnerability classified under CWE-1188, which involves the initialization of a resource with an insecure default configuration. 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, and if the underlying LDAP server permits anonymous binds, an attacker can bypass authentication mechanisms, gaining unauthorized access to Vault-managed secrets and resources. The vulnerability affects confidentiality and integrity by allowing unauthorized access without requiring user interaction or prior authentication. The CVSS 3.1 score of 7.4 reflects a high severity, with network attack vector, high attack complexity, and no privileges or user interaction required. The vulnerability was publicly disclosed on November 21, 2025, and fixed in Vault Terraform Provider version 5.5.0. No known exploits have been reported in the wild to date. The issue highlights the risk of insecure default configurations in security-critical infrastructure-as-code tools, emphasizing the need for secure defaults and thorough configuration reviews.

For European organizations, this vulnerability poses a significant risk to the confidentiality and integrity of sensitive data managed via HashiCorp Vault, especially in environments leveraging LDAP for authentication. Unauthorized access could lead to exposure of secrets, credentials, and other sensitive configuration data, potentially enabling further lateral movement or privilege escalation within corporate networks. Organizations with automated infrastructure provisioning and secrets management pipelines are particularly vulnerable. The impact is heightened in sectors with stringent data protection requirements, such as finance, healthcare, and government, where unauthorized data access can lead to regulatory penalties and reputational damage. Additionally, the vulnerability could undermine trust in DevOps and cloud security practices, delaying adoption of automation tools. Although no availability impact is expected, the breach of confidentiality and integrity alone justifies urgent remediation.

European organizations should immediately upgrade to Vault Terraform Provider version 5.5.0 or later, where the deny_null_bind parameter default is corrected. Until upgrade, administrators must manually set deny_null_bind to true in LDAP auth method configurations to prevent anonymous binds. Conduct thorough audits of LDAP server settings to ensure anonymous or unauthenticated binds are disabled at the directory service level. Implement network segmentation and access controls to limit exposure of Vault and LDAP servers to trusted hosts only. Monitor authentication logs for unusual bind attempts or access patterns indicative of exploitation attempts. Incorporate configuration management and security scanning tools to detect insecure defaults in infrastructure-as-code deployments. Provide training to DevOps and security teams on secure configuration best practices for HashiCorp tools. Finally, maintain an incident response plan tailored to secrets management breaches to quickly contain and remediate any compromise.