SillyTavern: SSRF vulnerability in the CORS proxy middleware

SillyTavern is a locally installed user interface that allows users to interact with text generation large language models, image generation engines, and text-to-speech voice models. Prior to 1.18.0, corsProxyMiddleware forwards req.params.url directly into fetch(url, ...). It only blocks circular requests to its own host and does not enforce destination allowlist or private/loopback restrictions, enabling SSRF. This vulnerability is fixed in 1.18.0.