{"id":"CVE-2026-54742","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-54742","generatedAt":"2026-10-28T00:19:48.531Z","title":"Lemmy is a link aggregator and forum for the fediverse.","description":"Lemmy is a link aggregator and forum for the fediverse. From 0.19.18 until 0.19.19 and 1.0.0-alpha.20, a community moderator can feature or unfeature posts in other communities through federated CollectionAdd and CollectionRemove activities using CollectionType::Featured. After verify_mod_action authorizes the actor against self.community(), the receive handlers in crates/apub/activities/src/community/collection_add.rs and crates/apub/activities/src/community/collection_remove.rs dereference self.object as an ApubPost and update featured_community without verifying that post.community_id equals community.id. A moderator can therefore target an unrelated post owned by another community, push it into featured feeds and listings, or undo another community's legitimate curation decision. This issue is fixed in versions 0.19.19 and 1.0.0-alpha.20.","published":"2026-08-19T20:17:17.000Z","lastModified":"2026-09-09T21:16:00.000Z","status":"Deferred","sourceIdentifier":"security-advisories@github.com","cvss":{"version":"4.0","score":5.1,"severity":"MEDIUM","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M"},"cwe":["CWE-863"],"affected":[],"epss":{"score":0.00548,"percentile":0.45623,"date":"2026-10-26","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"low","text":"Lower severity and a low EPSS score (0.55%). Track it; it rarely justifies an emergency change on its own."},"changes":[],"references":[{"url":"https://github.com/LemmyNet/lemmy/commit/108d78c592cc88bac2b0bf52ca6631be54f6fb23","source":"security-advisories@github.com"},{"url":"https://github.com/LemmyNet/lemmy/commit/abe256243822526dcd4bca857f7c0adeb49944f5","source":"security-advisories@github.com"},{"url":"https://github.com/LemmyNet/lemmy/pull/6500","source":"security-advisories@github.com"},{"url":"https://github.com/LemmyNet/lemmy/pull/6501","source":"security-advisories@github.com"},{"url":"https://github.com/LemmyNet/lemmy/releases/tag/0.19.19","source":"security-advisories@github.com"},{"url":"https://github.com/LemmyNet/lemmy/releases/tag/1.0.0-alpha.20","source":"security-advisories@github.com"},{"url":"https://github.com/LemmyNet/lemmy/security/advisories/GHSA-gwfj-h8r7-792v","source":"security-advisories@github.com"},{"url":"https://join-lemmy.org/news/2026-06-09_-_Lemmy_Release_v0.19.19","source":"security-advisories@github.com"},{"url":"https://github.com/LemmyNet/lemmy/security/advisories/GHSA-gwfj-h8r7-792v","source":"134c704f-9b21-4f2e-91b3-4a467353bcc0"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-54742","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}