CVE-2026-17266 Overview
CVE-2026-17266 is a path traversal vulnerability affecting IBM i versions 7.6, 7.5, 7.4, and 7.3. The flaw stems from improper limitation of a pathname to a restricted directory [CWE-22]. A remote authenticated attacker can exploit this weakness to access files outside the intended directory scope and obtain sensitive information from the host system.
Critical Impact
An authenticated remote attacker can read sensitive files stored outside restricted directories on affected IBM i systems, exposing confidential data.
Affected Products
- IBM i 7.6
- IBM i 7.5
- IBM i 7.4
- IBM i 7.3
Discovery Timeline
- 2026-08-12 - CVE CVE-2026-17266 published to NVD
- 2026-08-12 - Last updated in NVD database
Technical Details for CVE-2026-17266
Vulnerability Analysis
The vulnerability exists in IBM i's handling of file path inputs. The affected component fails to properly restrict pathnames to an intended directory boundary. An authenticated user can supply crafted path sequences to traverse the directory tree and reach files outside the permitted scope.
Successful exploitation results in unauthorized disclosure of file contents. The scope is limited to confidentiality; integrity and availability of the system are not directly affected. Because the attacker must hold valid credentials, the impact is bounded to the privileges of the authenticated account interacting with the vulnerable interface.
Root Cause
The root cause is insufficient validation and canonicalization of user-supplied path input [CWE-22]. When the application resolves file paths, it does not adequately filter directory traversal sequences such as ../ or absolute path references. As a result, requests targeting locations outside the intended restricted directory succeed rather than being rejected.
Attack Vector
The attack requires network access to a vulnerable IBM i interface and valid low-privilege authentication. No user interaction is required. An attacker submits a request containing a manipulated pathname parameter that traverses out of the intended directory. The server processes the path and returns the contents of the targeted file. See the IBM Support Page for vendor-specific technical detail.
Detection Methods for CVE-2026-17266
Indicators of Compromise
- Requests to IBM i services containing directory traversal sequences such as ../, ..\, or URL-encoded variants like %2e%2e%2f.
- Access attempts to sensitive system paths outside expected application directories from authenticated user sessions.
- Unusual read activity against configuration files, credential stores, or system libraries by low-privilege accounts.
Detection Strategies
- Inspect application and web server logs on IBM i hosts for path traversal patterns in request parameters and URI segments.
- Correlate authenticated session activity with file-access telemetry to identify accounts reading files outside their normal working set.
- Deploy signatures on network security devices to flag traversal payloads targeting IBM i management and file transfer interfaces.
Monitoring Recommendations
- Enable auditing on IBM i integrated file system objects containing sensitive data and alert on unexpected read events.
- Monitor authentication logs for successful low-privilege logins followed by anomalous file access patterns.
- Baseline normal API and service usage per user account and alert on deviations that involve path parameters.
How to Mitigate CVE-2026-17266
Immediate Actions Required
- Apply the vendor-provided fixes referenced on the IBM Support Page for IBM i 7.6, 7.5, 7.4, and 7.3.
- Review and reduce privileges of user accounts that can authenticate to exposed IBM i services.
- Restrict network exposure of IBM i management and file transfer interfaces to trusted administrative networks only.
Patch Information
IBM has published guidance for this vulnerability on its support portal. Administrators should consult the IBM Support Page for the specific PTF (Program Temporary Fix) numbers applicable to each affected release of IBM i.
Workarounds
- Enforce strict access controls on sensitive integrated file system directories to limit what authenticated users can read.
- Place a filtering proxy or web application firewall in front of exposed IBM i services to block traversal payloads.
- Rotate credentials for accounts with access to the vulnerable interface if compromise is suspected.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
