CVE-2026-92164

## Summary `HTTPSession` mounts a `FileAdapter` for the `file://` scheme and inherits redirect handling unchanged from `requests.Session`. `requests` does not check for scheme downgrades or cross-protocol transitions when it follows a redirect, so any http(s) request Streamlink makes can be redirected by the remote server into `file:///...` and the local file is returned as the response body. `GHSA-hgqw-6m45-hw5f` / `CVE-2026-44353` fixed direct `file://` segment and playlist URIs in HLS playlists and DASH manifests. Those checks look at the URL as it appears in the manifest, so a manifest that lists an ordinary `https://` URL passes them, and the redirect happens later at fetch time. The attack surface is the same one that advisory describes, but the flaw is one level down in `HTTPSession` rather than in the streaming implementations, so it applies to every request the session makes and not only to segment and manifest fetches. ## Affected version Executed against released `streamlink 8.5.0` (PyPI, installed into a clean venv on Python 3.12). ## Attacker model The attacker controls a URL the victim's Streamlink run reaches: a playlist or manifest URL passed on the command line, or any http(s) URL referenced from attacker-controlled manifest content. No privileges on the victim host and no `file://` input are required, and the `file://` scheme never appears in anything the victim or the manifest parser sees. ## Proof of concept, executed ```python import threading from http.server import BaseHTTPRequestHandler, HTTPServer from streamlink.exceptions import StreamError from streamlink.session.http import HTTPSession class H(BaseHTTPRequestHandler): def do_GET(self): if self.path == "/segment": self.send_response(302) self.send_header("Location", "file:///etc/hosts") self.end_headers() else: self.send_response(404) self.end_headers() def log_message(self, *a): pass s