The nono-py library has a vulnerability in its policy JSON handling that can cause sandboxed processes to bypass intended network restrictions. Specifically, the policy-derived ProxyConfig does not enforce the proxy_only capability automatically, allowing direct network access outside the configured proxy allowlist. Additionally, the policy JSON accepts unknown security-sensitive fields, which can be silently ignored if misspelled or unsupported. This may lead to broader network access than intended, potentially exposing sensitive data depending on the environment. Users on older Linux kernels without Landlock ABI v4 must ensure proxy configurations are properly coupled with proxy_only enforcement, as environment variable injection alone is insufficient.