CVE-2026-18106 Overview
CVE-2026-18106 is an information disclosure vulnerability affecting IBM i versions 7.6, 7.5, 7.4, and 7.3. The flaw stems from improper validation of user-supplied path input, which is classified as a path traversal weakness [CWE-22]. A remote authenticated attacker can leverage this weakness to access sensitive information outside of intended directory boundaries.
The vulnerability requires network access and valid low-privilege credentials to exploit. It does not require user interaction and can be triggered with low attack complexity. IBM has published guidance for affected customers through its support portal.
Critical Impact
A remote authenticated attacker can obtain sensitive information from the IBM i system by supplying crafted path input that bypasses validation controls.
Affected Products
- IBM i 7.6
- IBM i 7.5
- IBM i 7.4
- IBM i 7.3
Discovery Timeline
- 2026-08-12 - CVE-2026-18106 published to NVD
- 2026-08-12 - Last updated in NVD database
Technical Details for CVE-2026-18106
Vulnerability Analysis
CVE-2026-18106 is a path traversal vulnerability [CWE-22] in IBM i. The affected component fails to properly validate or sanitize path segments provided by the user. As a result, sequences such as ../ can be interpreted literally by the underlying file resolution logic.
This allows an authenticated actor to reference files outside of the directory the application is expected to serve. The impact is limited to confidentiality, meaning attackers can read data but cannot modify it or disrupt service through this flaw alone.
Root Cause
The root cause is insufficient input validation on path parameters supplied over the network. The vulnerable code path accepts operator-controlled input and passes it to a file system operation without canonicalizing or restricting the resolved path. Refer to the IBM Support Page for vendor-specific component details.
Attack Vector
Exploitation requires network reachability to the affected IBM i service and valid low-privilege authentication. The attacker submits a request containing crafted path traversal sequences targeting files of interest, such as configuration files or application data. The server returns the contents of the referenced file to the attacker.
No exploit code is publicly available at the time of publication, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog. See the IBM Support Page for technical details.
Detection Methods for CVE-2026-18106
Indicators of Compromise
- Request logs containing path traversal sequences such as ../, ..\, or URL-encoded variants like %2e%2e%2f targeting IBM i services.
- Unexpected read access to sensitive files by low-privilege user accounts on IBM i systems.
- Access attempts to files outside the expected working directory of the affected service.
Detection Strategies
- Inspect application and web server logs for path traversal patterns in URL parameters, form fields, and API request bodies.
- Correlate authenticated session activity with anomalous file access patterns on IBM i integrated file system (IFS) paths.
- Alert on repeated 4xx or 5xx responses following requests containing encoded traversal sequences, which may indicate probing.
Monitoring Recommendations
- Enable IBM i audit journal entries for object access and forward them to a centralized SIEM for correlation.
- Monitor authenticated user activity for deviations from established baselines, particularly file read volumes.
- Track access to sensitive configuration paths and application data directories.
How to Mitigate CVE-2026-18106
Immediate Actions Required
- Apply the IBM-supplied fix or PTF as documented on the IBM Support Page for versions 7.6, 7.5, 7.4, and 7.3.
- Review and reduce privileges assigned to authenticated users of the affected IBM i services.
- Audit recent access logs for evidence of path traversal attempts against the affected services.
Patch Information
IBM has published remediation guidance on its support portal. Administrators should review the IBM Support Page and apply the corresponding Program Temporary Fix (PTF) for each affected IBM i release.
Workarounds
- Restrict network access to affected IBM i services using firewall rules or IP allow lists until patches are applied.
- Enforce strong authentication and remove unused user profiles to reduce the population of accounts that could exploit the flaw.
- Deploy web application firewall rules to block requests containing path traversal sequences targeting IBM i endpoints.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
