{"apiVersion":"1.0","identifier":"CVE-2026-54740","description":"Lemmy is a link aggregator and forum for the fediverse. Prior to 0.19.19 and 1.0.0-alpha.18, a lower-ranked remote moderator can remove a higher-ranked moderator by sending a signed ActivityPub Remove activity to the target instance. The local API uses LocalUser::is_higher_mod_or_admin_check to enforce moderator rank, but CollectionRemove::verify in crates/apub/activities/src/community/collection_remove.rs only calls verify_mod_action. CollectionRemove::receive dereferences self.object as an ApubPerson, creates a CommunityModeratorForm, and calls CommunityActions::leave without checking that the actor outranks the moderator identified by the object field. In communities with federated moderators, a junior moderator can therefore strip senior moderators from the community moderator list even though the local API rejects the same action. This issue is fixed in versions 0.19.19 and 1.0.0-alpha.18.","publishedAt":"2026-08-19T21:16:58","lastModifiedAt":"2026-08-20T20:17:35","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-54740","cvssScore":6.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N","epssProbability":0.00311,"riskScore":0.67,"affectedProduct":"Lemmy","affectedVersions":"<0.19.19, <1.0.0-alpha.18","vulnerabilityType":"Web app","operatingSystems":[],"links":{"self":"https://www.redsauce.net/api/cves/CVE-2026-54740","webPages":{"es":"https://www.redsauce.net/es/cves/CVE-2026-54740","en":"https://www.redsauce.net/en/cves/CVE-2026-54740","fr":"https://www.redsauce.net/fr/cves/CVE-2026-54740","pt":"https://www.redsauce.net/pt/cves/CVE-2026-54740","de":"https://www.redsauce.net/de/cves/CVE-2026-54740","sk":"https://www.redsauce.net/sk/cves/CVE-2026-54740","el":"https://www.redsauce.net/el/cves/CVE-2026-54740"},"source":"https://nvd.nist.gov/vuln/detail/CVE-2026-54740"}}