CVE-2026-79715 in WebSphere Application Server
Summary
by MITRE • 10/14/2026
IBM WebSphere Application Server - Liberty 17.0.0.3 through 26.0.0.9 could allow a local attacker to traverse directories on the system. An attacker could use a specially crafted application archive to write files outside the intended directory.
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Analysis
by VulDB Data Team • 10/14/2026
The vulnerability identified in IBM WebSphere Application Server Liberty versions ranging from 17.0.0.3 through 26.0.0.9 represents a critical path traversal flaw that compromises the integrity of file system operations within the application server environment. This security defect allows for unauthorized directory traversal, enabling an attacker to manipulate the location where files are written during deployment or extraction processes. The core technical issue stems from insufficient validation of archive contents and paths when handling specially crafted application archives. When a user uploads or deploys an archive containing maliciously constructed file paths that include relative path sequences such as dot-dot-slash notation, the server fails to properly sanitize these inputs before processing them for storage on the underlying operating system's file structure.
From a technical perspective, this flaw is classified under CWE-22: Improper Limitation of a Pathname to a Restricted Directory, which describes vulnerabilities where software does not sufficiently neutralize special elements within a pathname that can cause the path to refer to locations outside of the intended restricted directory. The operational mechanism involves an attacker crafting an archive file with entries designed to escape the designated deployment or temporary directories. By leveraging these crafted paths, the application server inadvertently writes files to arbitrary locations on the host system rather than confining them to the expected sandboxed area. This behavior violates the principle of least privilege and proper isolation boundaries that are essential for secure web application servers.
The impact of this vulnerability is significant because it grants a local attacker the ability to write files outside the intended directory structure. If an attacker has access to deploy applications or upload archives within the Liberty server environment, they can exploit this flaw to overwrite critical system configuration files, inject malicious scripts into executable directories, or place backdoors in locations that are accessible by other services running on the same host. This capability effectively breaks the isolation between different web applications and the underlying operating system, potentially leading to remote code execution if combined with other vulnerabilities such as arbitrary file read or server-side request forgery. The ability to write files anywhere on the filesystem undermines the security model of multi-tenant environments where multiple applications share the same Liberty instance.
This vulnerability aligns with ATT&CK technique T1505.003, which covers Server Software Component: Web Shell Installation, as an attacker could use this file write capability to deploy a web shell for persistent access. Additionally, it relates to T1083: File and Directory Discovery if the traversal is used in conjunction with other flaws to map out the system structure before writing malicious content. The risk is particularly acute in environments where developers or automated build systems have elevated privileges within the application server context, as these actors are often trusted implicitly by the deployment mechanisms that contain this flaw.
Mitigation strategies must focus on both immediate remediation and long-term architectural improvements. IBM has released patches for versions 17.0.0.3 through 26.0.0.9 to address this issue, so upgrading to a patched version is the primary recommendation. Organizations should ensure that their patch management processes are updated to prioritize security fixes related to input validation and path handling in application servers. In addition to updating software, administrators should enforce strict least-privilege principles by running WebSphere Liberty with minimal operating system permissions. This includes configuring the server process to run under a dedicated user account with restricted file system access rights that limit write operations strictly to necessary directories. Furthermore, implementing input validation at the deployment interface level can provide an additional layer of defense against malformed archive contents before they reach the vulnerable code paths within the application server core.