{"id":"CVE-2026-107843","state":"PUBLISHED","title":"Contao: The registration module re-sends activation mails on any unauthenticated POST, with no throttle and no captcha check","description":"Contao is an Open Source CMS. From version 4.1.0 until 5.3.50 and 5.7.12, ModuleRegistration::compile() enters its follow-up registration branch on any POST to a page containing the registration module without verifying FORM_SUBMIT or the preceding captcha result. resendActivationMail() can then invoke OptInToken::send() without rate limiting, allowing an unauthenticated attacker to cause repeated activation emails to be sent to an address with a pending registration and to determine whether that pending registration exists. The branch is reachable only when reg_activate is enabled and the target has an unconfirmed registration and opt-in token. This issue is fixed in versions 5.3.50 and 5.7.12.","publishedAt":"2026-10-09T19:21:32.011Z","updatedAt":"2026-10-13T17:08:23.664Z","severity":{"score":5.3,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["contao contao"],"affected":[{"vendor":"contao","product":"contao","versions":[{"version":">= 4.1.0, < 5.3.50","status":"affected"},{"version":">= 5.4.0-RC1, < 5.7.12","status":"affected"}]}],"references":["https://github.com/contao/contao/security/advisories/GHSA-mfxh-vp55-7gc6","https://github.com/contao/contao/commit/2ea6117f9049db7221679251cfc41e67d941a74b","https://github.com/contao/contao/releases/tag/5.3.50","https://github.com/contao/contao/releases/tag/5.7.12"],"weaknesses":["CWE-204","CWE-770"],"ingestedAt":"2026-10-29T20:10:23.711Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/107xxx/CVE-2026-107843.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-107843","state":"PUBLISHED","datePublished":"2026-10-09T19:21:32.011Z","dateUpdated":"2026-10-13T17:08:23.664Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-10-08T22:34:49.291Z"},"containers":{"cna":{"title":"Contao: The registration module re-sends activation mails on any unauthenticated POST, with no throttle and no captcha check","descriptions":[{"lang":"en","value":"Contao is an Open Source CMS. From version 4.1.0 until 5.3.50 and 5.7.12, ModuleRegistration::compile() enters its follow-up registration branch on any POST to a page containing the registration module without verifying FORM_SUBMIT or the preceding captcha result. resendActivationMail() can then invoke OptInToken::send() without rate limiting, allowing an unauthenticated attacker to cause repeated activation emails to be sent to an address with a pending registration and to determine whether that pending registration exists. The branch is reachable only when reg_activate is enabled and the target has an unconfirmed registration and opt-in token. This issue is fixed in versions 5.3.50 and 5.7.12."}],"affected":[{"vendor":"contao","product":"contao","versions":[{"version":">= 4.1.0, < 5.3.50","status":"affected"},{"version":">= 5.4.0-RC1, < 5.7.12","status":"affected"}]}],"references":[{"url":"https://github.com/contao/contao/security/advisories/GHSA-mfxh-vp55-7gc6","name":"https://github.com/contao/contao/security/advisories/GHSA-mfxh-vp55-7gc6","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/contao/contao/commit/2ea6117f9049db7221679251cfc41e67d941a74b","name":"https://github.com/contao/contao/commit/2ea6117f9049db7221679251cfc41e67d941a74b","tags":["x_refsource_MISC"]},{"url":"https://github.com/contao/contao/releases/tag/5.3.50","name":"https://github.com/contao/contao/releases/tag/5.3.50","tags":["x_refsource_MISC"]},{"url":"https://github.com/contao/contao/releases/tag/5.7.12","name":"https://github.com/contao/contao/releases/tag/5.7.12","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":5.3,"baseSeverity":"MEDIUM","confidentialityImpact":"LOW","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-204","lang":"en","description":"CWE-204: Observable Response Discrepancy","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-770","lang":"en","description":"CWE-770: Allocation of Resources Without Limits or Throttling","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-10-09T19:21:32.011Z"},"source":{"advisory":"GHSA-mfxh-vp55-7gc6","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-10-13T17:08:09.326334Z","id":"CVE-2026-107843","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-13T17:08:23.664Z"}}]}}}