CVE-2026-55087 Etherpad: x-proxy-path header reflected into admin HTML/JS/CSS (cache-poisoning XSS) and concatenated into redirect (open-redirect)

Etherpad is a real-time collaborative editor. From 2.1.0 until 3.1.0, Etherpad uses the attacker-controlled x-proxy-path request header in src/node/hooks/express/admin.ts when substituting paths into HTML, JavaScript, and CSS under /admin without sanitization, Vary: x-proxy-path, or Cache-Control...

PT-2026-76573

Name of the Vulnerable Software and Affected Versions Etherpad versions 2.1.0 through 3.0.0 Description Etherpad fails to properly sanitize the x-proxy-path request header, leading to two distinct issues when client-supplied headers reach the server. First, in src/node/hooks/express/admin.ts, the...