EUVD-2026-42050

Phoenix: Presence keys colliding with Object.prototype members break existence checks...

Phoenix: Presence keys colliding with `Object.prototype` members break existence checks

Summary The Phoenix JavaScript presence client assets/js/phoenix/presence.js tests whether a presence already exists using a bare truthiness check statekey rather than an own-property check. Because applications commonly track presences under a client-supplied username or id, the presence key can...

CVE-2026-56812

Improper Check for Unusual or Exceptional Conditions vulnerability in phoenixframework phoenix Presence JavaScript client allows an attacker with ordinary channel access to cause a persistent client-side denial of service against every viewer of a presence channel topic. This vulnerability is...

CVE-2026-56812

Improper Check for Unusual or Exceptional Conditions vulnerability in phoenixframework phoenix Presence JavaScript client allows an attacker with ordinary channel access to cause a persistent client-side denial of service against every viewer of a presence channel topic. This vulnerability is...

CVE-2026-56812

The Phoenix JavaScript presence client suffers a client-side denial of service due to an unsafe existence check in Presence.syncState() and Presence.syncDiff(). By using a bare truthiness test (state[key]) to detect existing presences, attacker-controlled keys that collide with Object.prototype (...

CVE-2026-56812 Phoenix JavaScript presence client crashes on presence keys colliding with Object.prototype members in Presence.syncState/syncDiff

Improper Check for Unusual or Exceptional Conditions vulnerability in phoenixframework phoenix Presence JavaScript client allows an attacker with ordinary channel access to cause a persistent client-side denial of service against every viewer of a presence channel topic. This vulnerability is...