{"document":{"category":"csaf_vex","csaf_version":"2.0","title":"CVE-2026-55666: Rocket.Chat: Email Parameter Fallback Leads To Account Takeover Within Apple OAuth","publisher":{"category":"vendor","name":"HarborGuard Database","namespace":"https://database.harborguard.co"},"tracking":{"id":"CVE-2026-55666","status":"final","version":"1","initial_release_date":"2026-06-24T21:06:55.637Z","current_release_date":"2026-06-24T21:06:55.637Z","revision_history":[{"date":"2026-06-24T21:06:55.637Z","number":"1","summary":"Initial machine-readable export from HarborGuard."}]},"distribution":{"tlp":{"label":"WHITE"},"text":"Public CVE data; freely redistributable."},"notes":[{"category":"description","text":"Rocket.Chat is an open-source, secure, fully customizable communications platform. Prior to 8.5.1, 8.4.4, 8.3.6, 8.2.6, 8.1.6, 8.0.7, and 7.10.13, in apps/meteor/app/apple/server/loginHandler.ts, handleIdentityToken parses a JWT issued by Apple during the OAuth flow. The try block checks for an email parameter. If the JWT does not contain an email address, the application falls back to accepting an arbitrary email value supplied directly in the request. Attackers are able to forge Apple JWTs that do not contain an email address and leverage this vulnerability to carry out account takeover attacks. This vulnerability is fixed in 8.5.1, 8.4.4, 8.3.6, 8.2.6, 8.1.6, 8.0.7, and 7.10.13.","title":"CVE description"}],"references":[{"category":"self","summary":"CVE-2026-55666 on HarborGuard Database","url":"https://database.harborguard.co/cve/CVE-2026-55666"},{"category":"external","summary":"CVE Record","url":"https://www.cve.org/CVERecord?id=CVE-2026-55666"},{"category":"external","summary":"https://github.com/RocketChat/Rocket.Chat/security/advisories/GHSA-wx3c-76rf-wpwf","url":"https://github.com/RocketChat/Rocket.Chat/security/advisories/GHSA-wx3c-76rf-wpwf"}]},"product_tree":{"branches":[{"category":"vendor","name":"RocketChat","branches":[{"category":"product_name","name":"Rocket.Chat","branches":[{"category":"product_version","name":">= 8.5.0-rc.0, < 8.5.1","product":{"name":"RocketChat Rocket.Chat >= 8.5.0-rc.0, < 8.5.1","product_id":"CSAFPID-1","product_identification_helper":{"cpe":"cpe:2.3:a:rocketchat:rocket.chat:*:*:*:*:*:*:*:*"}}},{"category":"product_version","name":">= 8.4.0-rc.0, < 8.4.4","product":{"name":"RocketChat Rocket.Chat >= 8.4.0-rc.0, < 8.4.4","product_id":"CSAFPID-2","product_identification_helper":{"cpe":"cpe:2.3:a:rocketchat:rocket.chat:*:*:*:*:*:*:*:*"}}},{"category":"product_version","name":">= 8.3.0-rc.0, < 8.3.6","product":{"name":"RocketChat Rocket.Chat >= 8.3.0-rc.0, < 8.3.6","product_id":"CSAFPID-3","product_identification_helper":{"cpe":"cpe:2.3:a:rocketchat:rocket.chat:*:*:*:*:*:*:*:*"}}},{"category":"product_version","name":">= 8.2.0-rc.0, < 8.2.6","product":{"name":"RocketChat Rocket.Chat >= 8.2.0-rc.0, < 8.2.6","product_id":"CSAFPID-4","product_identification_helper":{"cpe":"cpe:2.3:a:rocketchat:rocket.chat:*:*:*:*:*:*:*:*"}}},{"category":"product_version","name":">= 8.1.0-rc.0, < 8.1.6","product":{"name":"RocketChat Rocket.Chat >= 8.1.0-rc.0, < 8.1.6","product_id":"CSAFPID-5","product_identification_helper":{"cpe":"cpe:2.3:a:rocketchat:rocket.chat:*:*:*:*:*:*:*:*"}}},{"category":"product_version","name":">= 7.11.0-rc.0, < 8.0.7","product":{"name":"RocketChat Rocket.Chat >= 7.11.0-rc.0, < 8.0.7","product_id":"CSAFPID-6","product_identification_helper":{"cpe":"cpe:2.3:a:rocketchat:rocket.chat:*:*:*:*:*:*:*:*"}}},{"category":"product_version","name":"< 7.10.13","product":{"name":"RocketChat Rocket.Chat < 7.10.13","product_id":"CSAFPID-7","product_identification_helper":{"cpe":"cpe:2.3:a:rocketchat:rocket.chat:*:*:*:*:*:*:*:*"}}}]}]}]},"vulnerabilities":[{"cve":"CVE-2026-55666","title":"Rocket.Chat: Email Parameter Fallback Leads To Account Takeover Within Apple OAuth","notes":[{"category":"description","text":"Rocket.Chat is an open-source, secure, fully customizable communications platform. Prior to 8.5.1, 8.4.4, 8.3.6, 8.2.6, 8.1.6, 8.0.7, and 7.10.13, in apps/meteor/app/apple/server/loginHandler.ts, handleIdentityToken parses a JWT issued by Apple during the OAuth flow. The try block checks for an email parameter. If the JWT does not contain an email address, the application falls back to accepting an arbitrary email value supplied directly in the request. Attackers are able to forge Apple JWTs that do not contain an email address and leverage this vulnerability to carry out account takeover attacks. This vulnerability is fixed in 8.5.1, 8.4.4, 8.3.6, 8.2.6, 8.1.6, 8.0.7, and 7.10.13.","title":"CVE description"}],"product_status":{"known_affected":["CSAFPID-1","CSAFPID-2","CSAFPID-3","CSAFPID-4","CSAFPID-5","CSAFPID-6","CSAFPID-7"]},"scores":[{"cvss_v4":{"version":"4.0","vectorString":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N","baseScore":9.3,"baseSeverity":"CRITICAL"},"products":["CSAFPID-1","CSAFPID-2","CSAFPID-3","CSAFPID-4","CSAFPID-5","CSAFPID-6","CSAFPID-7"]}],"remediations":[{"category":"none_available","details":"No fixed version is published yet. Monitor the upstream advisory.","product_ids":["CSAFPID-1","CSAFPID-2","CSAFPID-3","CSAFPID-4","CSAFPID-5","CSAFPID-6","CSAFPID-7"]}]}]}