Trilium Notes is an open-source, cross-platform hierarchical note taking application for building large personal knowledge bases. Versions 0.102.1 and prior are vulnerable to Local File Inclusion, allowing an authenticated attacker to read sensitive arbitrary files from the server's filesystem. The uploadModifiedFileToAttachment function, which is called when a POST request is received to /api/attachments/{attachmentId}/upload-modified-file, replaces the content of the attachment with the content from another file (whose path is provided in filePath of Request body). After which the content of the attachment can be viewed at /api/attachments/{attachmentId}/download. This exposes sensitive system files such as SSH keys, credentials, configs, and OS files, potentially leading to remote code execution and compromise of co-hosted applications. This issue has been fixed in version 0.102.2.