CVE-2026-85242

Server-Side Request Forgery via Favicon Redirect to Local Network Resources in PlaywrightCapture

PlaywrightCapture contains a server-side request forgery (SSRF) vulnerability in its favicon retrieval functionality. When only_global_lookup is enabled, the application validates the initial favicon URL to prevent requests to localhost, loopback, or other non-public network addresses. However, redirects followed by aiohttp were not subjected to the same validation. An attacker able to influence the content of a page processed by PlaywrightCapture could specify a publicly reachable favicon URL that responds with an HTTP redirect to a local or otherwise restricted address, such as 127.0.0.1, localhost, or an internal network service. Because aiohttp automatically followed the redirect, the resulting request could bypass the application's local-address restrictions and cause the PlaywrightCapture host to issue HTTP requests to resources that should not be externally reachable. Depending on the services reachable from the PlaywrightCapture host and how retrieved favicon data is subsequently exposed or processed, this could be used to probe internal HTTP services or potentially obtain information from otherwise inaccessible endpoints. The patch introduces an aiohttp request middleware that applies the existing local-URL validation to every request in the redirect chain. Requests resolving to restricted/local destinations are rejected before they are issued.

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