CVE-2019-0201 in TimesTen In-Memory Database
Summary
by MITRE
An issue is present in Apache ZooKeeper 1.0.0 to 3.4.13 and 3.5.0-alpha to 3.5.4-beta. ZooKeeper’s getACL() command doesn’t check any permission when retrieves the ACLs of the requested node and returns all information contained in the ACL Id field as plaintext string. DigestAuthenticationProvider overloads the Id field with the hash value that is used for user authentication. As a consequence, if Digest Authentication is in use, the unsalted hash value will be disclosed by getACL() request for unauthenticated or unprivileged users.
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Analysis
by VulDB Data Team • 01/11/2026
The vulnerability in Apache ZooKeeper identified as CVE-2019-0201 represents a critical security flaw affecting versions ranging from 1.0.0 through 3.4.13 and 3.5.0-alpha to 3.5.4-beta. This issue stems from improper access control implementation within the getACL() command functionality, which fundamentally undermines the security model of the distributed coordination service. The flaw specifically manifests when ZooKeeper processes requests to retrieve Access Control Lists for nodes within its hierarchical namespace, creating a situation where sensitive authentication information becomes exposed to unauthorized parties.
The technical root cause of this vulnerability lies in the implementation of the DigestAuthenticationProvider component within ZooKeeper's authentication framework. When digest authentication is enabled, the system stores user credentials as hash values within the ACL Id field, which serves as a repository for authentication identifiers. However, the getACL() command fails to enforce proper permission checks before returning this information, resulting in the plaintext disclosure of unsalted hash values. This design flaw creates a direct information disclosure vulnerability where any user with access to the getACL() functionality can retrieve authentication hashes without proper authorization, effectively bypassing the security mechanisms intended to protect user credentials.
The operational impact of this vulnerability extends beyond simple information disclosure, creating significant risks for systems relying on ZooKeeper for critical coordination services. Attackers can exploit this weakness to obtain authentication hashes and subsequently attempt offline password cracking attacks, potentially compromising user accounts and gaining unauthorized access to the entire ZooKeeper ensemble. The vulnerability particularly affects environments where digest authentication is implemented, making it a serious concern for distributed systems that depend on ZooKeeper for service coordination and configuration management. This weakness directly violates security principles outlined in CWE-200, which addresses information exposure, and undermines the fundamental security model of authentication mechanisms.
The security implications of this vulnerability align with ATT&CK technique T1552.001, which covers credentials from password storage providers, and T1078, which addresses valid accounts. Organizations using affected versions of Apache ZooKeeper face elevated risk of credential compromise, especially in environments where multiple services rely on the same authentication infrastructure. The disclosure of unsalted hash values significantly reduces the computational complexity required for attackers to recover original passwords, making this vulnerability particularly dangerous in production environments. System administrators should immediately implement mitigations including upgrading to patched versions of ZooKeeper, disabling digest authentication where possible, or implementing additional network-level access controls to restrict exposure to this vulnerability.
This vulnerability demonstrates the critical importance of proper access control implementation in distributed systems and highlights the potential consequences of insufficient validation of authentication contexts within security-sensitive operations. The flaw represents a failure in the principle of least privilege, where sensitive information is exposed without proper authorization checks, creating a pathway for attackers to escalate their privileges and compromise the entire system. Organizations should conduct thorough security assessments of their ZooKeeper deployments to identify affected systems and implement comprehensive remediation strategies that address both the immediate vulnerability and broader security posture considerations.