CVE-2026-18104 in Db2 Mirror for i
Summary
by MITRE • 09/24/2026
IBM Db2 Mirror for i 7.6, 7.5, and 7.4 could allow a local attacker to obtain sensitive information due to the use of the AES Electronic Codebook (ECB) mode for encryption.
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Analysis
by VulDB Data Team • 09/24/2026
The vulnerability identified in IBM Db2 Mirror for i versions 7.6, 7.5, and 7.4 stems from the implementation of weak cryptographic practices during data protection operations. Specifically, the software utilizes the AES Electronic Codebook (ECB) mode for encrypting sensitive information stored within the database environment. This configuration flaw allows a local attacker with access to the system to potentially extract or infer confidential data that was intended to be protected by encryption mechanisms. The core issue lies not in the strength of the Advanced Encryption Standard algorithm itself, but rather in the specific operational mode selected for its application.
Electronic Codebook mode is widely recognized in cybersecurity as an insecure method for encrypting data because it lacks semantic security. In ECB mode, identical plaintext blocks are encrypted into identical ciphertext blocks without any form of initialization vector or chaining mechanism to introduce randomness. This deterministic behavior creates patterns in the ciphertext that can be analyzed by an adversary. If a local attacker gains access to the storage medium or memory where these encrypted blocks reside, they can perform statistical analysis on the resulting data. By observing repeated patterns in the ciphertext, the attacker may deduce structural information about the plaintext, such as file headers, database structures, or repetitive content within sensitive fields like names, addresses, or financial records.
From a technical perspective, this vulnerability represents a fundamental misunderstanding of cryptographic best practices for block ciphers. While AES is a robust symmetric-key algorithm, its security relies heavily on proper mode selection and key management. The use of ECB fails to hide data patterns effectively, making it unsuitable for protecting structured data or any information where redundancy exists. This flaw exposes the organization to risks associated with data leakage, even if encryption appears to be enabled in configuration settings. Attackers do not need to break the encryption mathematically; they merely exploit the lack of diffusion provided by the ECB mode to correlate ciphertext blocks with known plaintext structures.
The operational impact of this vulnerability is significant for organizations relying on IBM Db2 Mirror for i for data protection and high availability. Local attackers, which could include malicious insiders or users who have compromised a local account through other means such as privilege escalation exploits, can leverage this weakness to bypass the intended confidentiality controls. The exposure of sensitive information violates principles of least privilege and data integrity, potentially leading to regulatory non-compliance with standards that mandate strong encryption for stored data. Furthermore, the ability to infer data patterns undermines trust in the database system's security posture, as encrypted storage is often assumed to provide a high level of protection against unauthorized access.
To mitigate this vulnerability, it is imperative to reconfigure the encryption settings within IBM Db2 Mirror for i to utilize a more secure mode of operation. Modes such as Cipher Block Chaining (CBC) or Galois/Counter Mode (GCM) are recommended because they incorporate initialization vectors and chaining mechanisms that ensure identical plaintext blocks produce different ciphertext outputs. This randomness prevents pattern analysis and provides semantic security, ensuring that even if an attacker observes the encrypted data, they cannot easily deduce information about its contents. Organizations should also review their key management practices to ensure that encryption keys are rotated regularly and stored securely, separate from the encrypted data itself.
This issue aligns with Common Weakness Enumeration (CWE) category CWE-327, which covers the use of a broken or risky cryptographic algorithm. More specifically, it relates to CWE-649, which addresses reliance on obfuscation through security by obscurity rather than robust design, although in this case, the flaw is more accurately described as using an insecure mode of operation for encryption. In terms of MITRE ATT&CK framework tactics, this vulnerability facilitates Initial Access and Credential Access phases if local attackers use it to harvest sensitive credentials or personal identifiable information stored within the database. Remediation efforts should prioritize updating configuration profiles to enforce stronger cryptographic standards across all data storage operations in the affected versions of IBM Db2 Mirror for i.