CVE-2025-4166 in Vault Community
Summary
by MITRE • 05/02/2025
Vault Community and Vault Enterprise Key/Value (kv) Version 2 plugin may unintentionally expose sensitive information in server and audit logs when users submit malformed payloads during secret creation or update operations via the Vault REST API. This vulnerability, identified as CVE-2025-4166, is fixed in Vault Community 1.19.3 and Vault Enterprise 1.19.3, 1.18.9, 1.17.16, 1.16.20.
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Analysis
by VulDB Data Team • 09/12/2025
The vulnerability described in CVE-2025-4166 represents a critical information disclosure issue within HashiCorp Vault's Key/Value version 2 plugin implementation. This flaw specifically manifests when users submit malformed payloads during secret creation or update operations through the Vault REST API interface. The vulnerability stems from inadequate input validation and error handling mechanisms within the plugin's processing pipeline, where malformed data structures fail to be properly sanitized before being logged or processed by the underlying system components. The issue affects both Vault Community and Vault Enterprise editions, indicating a widespread impact across the product ecosystem. Security researchers identified that when the system encounters malformed inputs during secret operations, the error handling routines inadvertently include sensitive data elements within the generated log entries, potentially exposing confidential information to unauthorized parties who might have access to system logs.
The technical exploitation of this vulnerability occurs through carefully crafted API requests that contain malformed data structures designed to trigger specific error conditions within the Vault Key/Value plugin. When these malformed payloads are processed, the system's error handling mechanism fails to strip sensitive information from the error messages before logging them to server logs or audit trails. This behavior creates a situation where confidential secret data, cryptographic keys, or other sensitive material may be inadvertently written to log files that could be accessed by unauthorized personnel or systems with appropriate permissions. The vulnerability is classified as a logging information disclosure issue that aligns with CWE-209, which specifically addresses "Information Exposure Through an Error Message" and is also related to CWE-200, covering "Information Exposure". The flaw demonstrates poor input validation practices where the system does not adequately sanitize user-supplied data before it is processed and potentially logged, creating an attack surface that could be leveraged by threat actors to extract sensitive information from system logs.
The operational impact of CVE-2025-4166 extends beyond simple information disclosure to potentially compromise the integrity and confidentiality of the entire Vault deployment. When sensitive information appears in server logs, it creates a significant risk for organizations that may have log files accessible to unauthorized users or systems, particularly in environments where log access controls are not properly enforced. The vulnerability affects critical operational workflows involving secret management, where the exposure of cryptographic keys, database credentials, API tokens, or other sensitive data could lead to unauthorized access to protected systems and data repositories. Organizations relying on Vault for security orchestration may experience cascading security implications if attackers can correlate exposed information with other system components or access patterns, potentially leading to broader compromise of their security infrastructure. This vulnerability also impacts compliance requirements for organizations subject to regulatory frameworks such as pci dss, hipaa, or soc 2, where unauthorized disclosure of sensitive information in logs constitutes a violation of data protection standards and could result in significant regulatory penalties.
Mitigation strategies for CVE-2025-4166 require immediate implementation of the vendor-released patches for Vault Community 1.19.3 and Vault Enterprise versions 1.19.3, 1.18.9, 1.17.16, and 1.16.20. Organizations should prioritize upgrading their Vault installations to these patched versions to eliminate the vulnerability at its source. Additionally, security teams should implement enhanced log monitoring and filtering mechanisms to identify and remove sensitive information from log entries before they are stored or transmitted. The implementation of proper input validation and sanitization procedures should be enforced across all API endpoints to prevent malformed data from reaching the error handling layers. Organizations should also consider implementing log access controls and audit trails to limit who can view system logs, particularly in environments where multiple administrative users may have access to the same logging infrastructure. The mitigation approach aligns with ATT&CK technique T1562.001, which covers "T1562.001 - Impair Defenses: Disable or Modify Tools", and also addresses the broader category of T1070, "Indicator Removal on Host", by ensuring that sensitive data is not inadvertently preserved in system artifacts. Security teams should conduct thorough log reviews to identify any potential exposure that may have occurred prior to patching, and implement continuous monitoring to detect similar issues in other components of their security infrastructure.