Misskey is an open source, federated social media platform. In affected versions missing validation in "ApInboxService.update" allows an attacker to modify the result of polls belonging to another user. No authentication is required, except for a valid signature from any actor on any remote instance. Vulnerable Misskey instances will accept spoofed updates for remote polls. Local polls are unaffected. This issue has been addressed in version 2024.11.0-alpha.3. Users are advised to upgrade. There are no known workarounds for this vulnerability.