Summary
Missing validation in ApRequestService.signedGet allows an attacker to create fake user profiles that appear to be from a different instance than the one where they actually exist. These profiles can be used to impersonate existing users from the target instance.
Impact
Vulnerable Misskey instances will accept spoofed users as valid, allowing an attacker to impersonate users on another instance. Attackers have full control of the spoofed user and can post, renote, or otherwise interact like a real account.
Summary
Missing validation in
ApRequestService.signedGetallows an attacker to create fake user profiles that appear to be from a different instance than the one where they actually exist. These profiles can be used to impersonate existing users from the target instance.Impact
Vulnerable Misskey instances will accept spoofed users as valid, allowing an attacker to impersonate users on another instance. Attackers have full control of the spoofed user and can post, renote, or otherwise interact like a real account.