Microsoft Kiota honors a poisoned .kiota/workspace.json configuration file without validating the 'outputPath' parameter during 'kiota client generate' or 'kiota plugin generate' commands. A malicious repository or pull request can specify an absolute or path-traversing 'outputPath' that causes Kiota to write generated client files outside the intended workspace directory. This arbitrary file write vulnerability (CWE-22) affects Kiota version 1.32.4 (and earlier versions prior to 1.32.5). The issue was fixed in versions 1.29.1 and 1.32.5 by enforcing that 'outputPath' must be a relative subdirectory of the workspace root, rejecting absolute paths, UNC paths, and any '..' traversal segments. Generation aborts with an error if validation fails.

An attacker who can commit or submit a pull request with a malicious .kiota/workspace.json file can cause arbitrary file writes on the filesystem of any developer or CI system that runs the documented Kiota client or plugin generation commands. This can overwrite critical source or build files or drop malicious files in auto-loaded locations, potentially leading to code execution or supply chain compromise. The vulnerability arises from trusting unvalidated configuration data in the repository, representing a significant risk in collaborative development environments.

Upgrade to Microsoft Kiota version 1.29.1, 1.32.5, or later. These versions include validation that restricts the 'outputPath' configuration to relative paths within the workspace root, preventing path traversal. Additionally, review any committed .kiota/workspace.json files in your repositories to ensure 'outputPath' values do not point outside the workspace. If upgrading is not immediately possible, avoid running 'kiota client generate' or 'kiota plugin generate' commands on untrusted or unreviewed repositories or pull requests.