FreshRSS is a free, self-hostable RSS aggregator. In versions 1.26.3 and below, due to a bypass of double clickjacking protection (confirmation dialog), it is possible to trick the admin into clicking the Promote button in another user's management page after the admin double clicks on a button inside an attacker-controlled website. A successful attack can allow the attacker to promote themselves to "admin" and log into other users' accounts.

the attacker has to know the specific instance URL they're targeting. This issue is fixed in version 1.27.0.