CVE-2026-92811

browserless versions 1.44.0 through 2.56.7 fail to enforce file protocol restrictions in their Playwright websocket endpoints, allowing any authenticated token holder to read arbitrary files from the server. An attacker who possesses a valid connection token connects to the Playwright websocket and instructs the headless browser to navigate to file:// URLs, exfiltrating the contents of files accessible to the container process. This works even though the ALLOW_FILE_PROTOCOL setting defaults to false, meaning the security control is not actually enforced on the vulnerable endpoints. Any deployment of the affected versions that issues tokens to third parties, partners, or shared automation users is affected, which is a common pattern for browserless-style scraping and PDF-generation services. No public proof-of-concept, in-the-wild exploitation, or KEV listing is known.

What to do: Upgrade browserless to a release newer than 2.56.7 that enforces the file protocol restriction. Until patched, avoid issuing websocket tokens to untrusted clients, restrict network access to the Playwright websocket endpoints, and run the container with minimal filesystem read permissions. Review service logs for browser navigations to file:// URLs, which would indicate attempted abuse.