CVE-2026-44283 in etcd
Summary
by MITRE • 05/14/2026
etcd is a distributed key-value store for the data of a distributed system. Prior to 3.4.44, 3.5.30, and 3.6.11, a vulnerability in etcd allows read access via PrevKv, or lease attachment in Put requests within transaction operations, to bypass RBAC authorization checks. An authenticated user without sufficient read or lease-related permissions may be able to access unauthorized data or attach leases by invoking transaction operations with these features enabled. This vulnerability is fixed in 3.4.44, 3.5.30, and 3.6.11.
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Analysis
by VulDB Data Team • 05/19/2026
The vulnerability in etcd represents a critical authorization bypass flaw that undermines the security controls of distributed systems relying on this key-value store. This issue affects versions prior to 3.4.44, 3.5.30, and 3.6.11, where the access control mechanisms fail to properly validate user permissions during transaction operations. The flaw specifically targets the PrevKv and lease attachment functionality within Put requests, which are fundamental components of etcd's transaction processing capabilities. The vulnerability stems from insufficient validation of user credentials and permissions when these particular features are invoked within transaction contexts, creating a pathway for unauthorized access to protected data resources.
The technical implementation of this vulnerability exploits the transaction processing engine's failure to enforce proper authorization checks when PrevKv or lease attachment operations are performed within transactional requests. When an authenticated user executes a transaction containing a Put operation with these features enabled, the system should verify that the user possesses the necessary read permissions for the target key and lease-related privileges. However, the flaw allows malicious actors to bypass these checks by leveraging transaction operations that inherently support PrevKv functionality or lease attachment mechanisms. This creates a scenario where users with minimal privileges can access data they should not be able to read or attach leases to resources they do not have authorization to modify.
The operational impact of this vulnerability extends beyond simple data exposure, as it can enable attackers to manipulate system state through lease operations that control resource expiration and cleanup processes. An attacker with read access to unauthorized data can potentially gather sensitive information about system configuration, user credentials, or operational parameters that should remain protected. Additionally, the ability to attach unauthorized leases can disrupt system operations, cause resource exhaustion, or enable persistence mechanisms that maintain access even after initial compromise attempts. The vulnerability affects the fundamental security model of etcd deployments, particularly in environments where RBAC policies are enforced to maintain data isolation and access control boundaries.
Security mitigations for this vulnerability require immediate deployment of patched versions 3.4.44, 3.5.30, and 3.6.11, which contain proper authorization validation mechanisms for transaction operations. Organizations should also implement comprehensive monitoring of transaction operations, particularly those involving PrevKv and lease attachment features, to detect anomalous access patterns. The fix addresses the root cause by ensuring that all transaction operations properly validate user permissions before executing PrevKv retrieval or lease attachment operations, aligning with the principle of least privilege enforcement. This vulnerability classification aligns with CWE-284 Access Control Bypass and maps to ATT&CK technique T1078 Valid Accounts and T1566 Phishing, as it enables unauthorized access through legitimate authenticated sessions. Organizations should conduct thorough security assessments of their etcd deployments to ensure proper RBAC implementation and validate that all transaction operations properly enforce authorization controls, particularly in multi-tenant or highly regulated environments where data isolation is critical.