CVE-2026-82217: CWE-22 Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') in Eclipse Foundation Eclipse Theia

In Eclipse Theia versions 1.73.0 through before 1.75.0, the AI Agent Mode file-change tools (writeFileContent, suggestFileContent, and related helpers) improperly resolve file paths without verifying that they remain within the workspace directory. This allows an attacker to supply crafted relative paths (e.g., ../.bashrc), absolute paths, or ~-expanded paths to write or delete files outside the intended workspace boundary. Since the path argument can be influenced via indirect prompt injection through the AI model output, and writes occur without user confirmation, this vulnerability can be exploited to modify critical host files such as shell startup scripts or SSH authorized keys, potentially leading to backend code execution.

Successful exploitation allows an attacker to write or delete arbitrary files on the host system with the privileges of the Theia backend OS user. This can lead to privilege escalation and remote code execution by modifying sensitive files like shell startup scripts or SSH authorized keys. The vulnerability has a high severity with a CVSS score of 8.8, reflecting its potential for significant confidentiality, integrity, and availability impact.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, restrict access to the AI Agent Mode features and monitor usage closely. Avoid running Theia backend services with elevated privileges to limit potential impact.