Medium [CVE-2026-71492] Arbitrary file write via path traversal

Banks generates meaningful LLM prompts using a simple template language. Prior to version 2.4.5, DirectoryPromptRegistry.set() in src/banks/registries/directory.py interpolates attacker-controlled Prompt.name and Prompt.version values into a Path without canonicalization or containment validation.

Relative traversal such as../victim/foo and an absolute Prompt.name can escape or discard the configured registry root, while overwrite=True permits replacement of existing target files. The poisoned name is persisted in index.json and reconstructed by _load(), allowing the out-of-root path to survive later registry loads.

An application that forwards request data into these fields can therefore write Prompt.raw bytes to attacker-chosen paths writable by the application process. This issue is fixed in version 2.4.5.

A flaw was found in Banks. This allows for path traversal, enabling an attacker to write arbitrary files outside the intended registry root.

This vulnerability could lead to unauthorized modification of files on the system where Banks is running. The 'banks' library is vulnerable to arbitrary file write via path traversal when an application processes attacker-controlled input for prompt names or versions.

This flaw allows an attacker to write arbitrary files to locations writable by the application process, potentially leading to system compromise.