{"id":"CVE-2026-72722","state":"PUBLISHED","title":"Discourse: Duplicate lookup reveals restricted topic titles through canonicalized URLs","description":"Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, TopicLink.extract_from, TopicLink.ensure_entry_for, and TopicLink.duplicate_lookup do not consistently enforce Guardian.can_see? checks when processing internal links. An authenticated user can submit links to restricted topics, private messages, or hidden posts and receive canonicalized slugs or titles in the composer_messages duplicate_lookup response even though the targets are not visible to that user. This issue is fixed in versions 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0.","publishedAt":"2026-08-10T15:54:35.907Z","updatedAt":"2026-08-13T17:46:27.779Z","severity":{"score":4.3,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["discourse discourse"],"affected":[{"vendor":"discourse","product":"discourse","versions":[{"version":"< 2026.1.6","status":"affected"},{"version":">= 2026.5.0-latest, < 2026.5.2","status":"affected"},{"version":">= 2026.6.0-latest, < 2026.6.1","status":"affected"},{"version":">= 2026.7.0-latest, < 2026.7.0","status":"affected"}]}],"references":["https://github.com/discourse/discourse/security/advisories/GHSA-4fx9-5m29-83p4","https://github.com/discourse/discourse/pull/42091","https://github.com/discourse/discourse/pull/42092","https://github.com/discourse/discourse/pull/42093","https://github.com/discourse/discourse/pull/42094","https://github.com/discourse/discourse/commit/45abd925e46e8be40d2d047bced26628f26e4e31","https://github.com/discourse/discourse/commit/7d7ce546ac86e24a6512b321ace69fc52fe37bf4","https://github.com/discourse/discourse/commit/836a251d54a1004fb1c463a7d299b933b176191f","https://github.com/discourse/discourse/commit/e54ba27eacee0f14f315e510e287e7ac2e4bdb1a"],"weaknesses":["CWE-862"],"ingestedAt":"2026-10-29T20:12:58.252Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/72xxx/CVE-2026-72722.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-72722","state":"PUBLISHED","datePublished":"2026-08-10T15:54:35.907Z","dateUpdated":"2026-08-13T17:46:27.779Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-08-10T13:48:09.545Z"},"containers":{"cna":{"title":"Discourse: Duplicate lookup reveals restricted topic titles through canonicalized URLs","descriptions":[{"lang":"en","value":"Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, TopicLink.extract_from, TopicLink.ensure_entry_for, and TopicLink.duplicate_lookup do not consistently enforce Guardian.can_see? checks when processing internal links. An authenticated user can submit links to restricted topics, private messages, or hidden posts and receive canonicalized slugs or titles in the composer_messages duplicate_lookup response even though the targets are not visible to that user. This issue is fixed in versions 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0."}],"affected":[{"vendor":"discourse","product":"discourse","versions":[{"version":"< 2026.1.6","status":"affected"},{"version":">= 2026.5.0-latest, < 2026.5.2","status":"affected"},{"version":">= 2026.6.0-latest, < 2026.6.1","status":"affected"},{"version":">= 2026.7.0-latest, < 2026.7.0","status":"affected"}]}],"references":[{"url":"https://github.com/discourse/discourse/security/advisories/GHSA-4fx9-5m29-83p4","name":"https://github.com/discourse/discourse/security/advisories/GHSA-4fx9-5m29-83p4","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/discourse/discourse/pull/42091","name":"https://github.com/discourse/discourse/pull/42091","tags":["x_refsource_MISC"]},{"url":"https://github.com/discourse/discourse/pull/42092","name":"https://github.com/discourse/discourse/pull/42092","tags":["x_refsource_MISC"]},{"url":"https://github.com/discourse/discourse/pull/42093","name":"https://github.com/discourse/discourse/pull/42093","tags":["x_refsource_MISC"]},{"url":"https://github.com/discourse/discourse/pull/42094","name":"https://github.com/discourse/discourse/pull/42094","tags":["x_refsource_MISC"]},{"url":"https://github.com/discourse/discourse/commit/45abd925e46e8be40d2d047bced26628f26e4e31","name":"https://github.com/discourse/discourse/commit/45abd925e46e8be40d2d047bced26628f26e4e31","tags":["x_refsource_MISC"]},{"url":"https://github.com/discourse/discourse/commit/7d7ce546ac86e24a6512b321ace69fc52fe37bf4","name":"https://github.com/discourse/discourse/commit/7d7ce546ac86e24a6512b321ace69fc52fe37bf4","tags":["x_refsource_MISC"]},{"url":"https://github.com/discourse/discourse/commit/836a251d54a1004fb1c463a7d299b933b176191f","name":"https://github.com/discourse/discourse/commit/836a251d54a1004fb1c463a7d299b933b176191f","tags":["x_refsource_MISC"]},{"url":"https://github.com/discourse/discourse/commit/e54ba27eacee0f14f315e510e287e7ac2e4bdb1a","name":"https://github.com/discourse/discourse/commit/e54ba27eacee0f14f315e510e287e7ac2e4bdb1a","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":4.3,"baseSeverity":"MEDIUM","confidentialityImpact":"LOW","integrityImpact":"NONE","privilegesRequired":"LOW","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-862","lang":"en","description":"CWE-862: Missing Authorization","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-08-10T15:54:35.907Z"},"source":{"advisory":"GHSA-4fx9-5m29-83p4","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-08-13T17:46:20.910196Z","id":"CVE-2026-72722","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-08-13T17:46:27.779Z"}}]}}}