CVE-2026-15955 in Db2
Summary
by MITRE • 09/14/2026
IBM Db2 11.5.0 through 11.5.9, and 12.1.0 through 12.1.5 could allow a remote attacker to perform an arbitrary file write due to improper validation of file paths.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 09/14/2026
The vulnerability identified in IBM Db2 versions 11.5.0 through 11.5.9 and 12.1.0 through 12.1.5 represents a critical security flaw rooted in the application's handling of user-supplied input during file system operations. Specifically, the database management system fails to adequately validate or sanitize file paths provided by remote attackers before utilizing them for write operations. This improper validation allows an attacker to manipulate the intended destination directory, effectively bypassing standard access controls and sandboxing mechanisms that are typically enforced by relational database engines to protect underlying operating system resources. The core technical flaw lies in the lack of rigorous path canonicalization or restriction checks, which permits the use of relative paths, symbolic links, or absolute paths outside the designated secure directories. By exploiting this weakness, a remote attacker can direct write operations to arbitrary locations on the host file system where the database server is running.
From an operational perspective, the impact of this vulnerability extends far beyond simple data corruption within the database itself. An arbitrary file write capability grants the attacker significant leverage over the underlying operating environment. Depending on the privileges under which the Db2 service runs, typically a dedicated user account with elevated permissions to manage database files and logs, the attacker can overwrite critical system configuration files, replace legitimate executables with malicious payloads, or modify application-specific scripts that are executed by higher-privileged processes such as root or SYSTEM accounts. This scenario creates a direct pathway for privilege escalation, allowing an unauthenticated remote actor to achieve full control over the compromised host. The ability to write arbitrary files also facilitates persistence mechanisms, where attackers can install backdoors or web shells to maintain access even after initial detection and remediation attempts are made by security teams.
This vulnerability aligns with Common Weakness Enumeration (CWE) category CWE-22: Improper Limitation of a Pathname to a Restricted Directory, commonly known as path traversal. Furthermore, the exploitation technique maps directly to MITRE ATT&CK tactic TA0004: Privilege Escalation and specifically techniques such as T1564: Hidden Files and Directories or T1204: User Execution if the written files are designed to be executed by users or scheduled tasks. The lack of input validation on file paths is a classic implementation error that underscores the importance of strict adherence to secure coding practices, particularly when dealing with external inputs in server-side applications. Attackers can leverage this flaw through various vectors depending on how Db2 exposes its interfaces, potentially via SQL injection points, administrative APIs, or specific database features that allow for file system interaction such as loading data from files or exporting results.
Mitigation strategies must focus on both immediate remediation and long-term architectural improvements. The primary defense is to apply the latest security patches provided by IBM, which address this validation gap by enforcing strict path restrictions and sanitizing all user-supplied directory inputs before they are processed by the file system APIs. Organizations should ensure that their Db2 instances are updated to versions beyond 11.5.9 and 12.1.5 as soon as these patches are available in a tested environment. In addition to patching, it is crucial to enforce least-privilege principles for the database service account. By running the Db2 instance under a restricted user account with minimal permissions on the operating system file structure, even if an attacker successfully exploits this vulnerability, their ability to impact critical system components or escalate privileges will be significantly limited. Regular auditing of file access logs and monitoring for unusual write activities in non-standard directories can also aid in early detection of exploitation attempts.