Advisories for Cargo/Lemmy_api package

read_multi_community() does not enforce the private-instance setting. On a private instance, an unauthenticated visitor can read multi-community names, titles, summaries, sidebars, owner identities, and member community lists. mid = api("POST", "/multi_community", admin, json={ "name": "m" + suffix, "title": secret, "summary": secret + " summary", "sidebar": secret + " sidebar", }).json()["multi_community_view"]["multi"]["id"]

The unauthenticated resend-verification endpoint returns different responses for registered and unregistered email addresses. A malicious third party can submit candidate addresses to /api/v4/account/auth/resend_verification_email and distinguish accounts from misses.

Lemmy applies private-community checks in PostView and CommentView, but several adjacent API views skip the accepted-follower filter. Bob, a registered user who is not an accepted follower, can read private community sidebar and summary fields. Alice, a former accepted follower, can still read saved and liked private post bodies after she leaves. An unauthenticated visitor can read private community metadata and removed private post names through the modlog.