{"schema":"threatline.record/2","record":{"id":"CVE-2026-107843","aliases":["GHSA-mfxh-vp55-7gc6"],"summary":"Contao: The registration module re-sends activation mails","details":"`ModuleRegistration::compile()` reaches its follow-up registration branch on **any** POST to a page carrying the module. That branch checks neither `FORM_SUBMIT` nor the captcha result computed immediately above it, and `resendActivationMail()` leads to `OptInToken::send()`, which has no rate limit at all.\n\n### Impact\n\nAnyone on the internet can make a Contao installation send unlimited mail to an address of their choosing, from the site's own sender and reputation, at one outbound message per HTTP request. That is both a nuisance for the recipient and a deliverability risk for the site operator. The same request is a reliable account oracle for \"this address has a pending registration on this site\", which is exactly the sort of membership fact a public site is usually expected not to disclose.\n\n**Honest bound.** The target must have an unconfirmed registration, that is `tl_member.disable = 1` together with an unconfirmed `reg-` opt-in token. An attacker can create that state for an arbitrary address, since registration requires no ownership proof, but on a site where `reg_activate` is off the branch is unreachable.","categories":["Libraries & packages"],"product":"contao/core-bundle","vendor":"contao","ecosystem":"composer","affected_ranges":[{"source":"GitHub Advisory Database","source_url":"https://github.com/advisories/GHSA-mfxh-vp55-7gc6","source_modified_at":"2026-10-09T20:54:07Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"ecosystem":"composer","name":"contao/core-bundle"},"range":">= 4.1.0, < 5.3.50"},{"source":"GitHub Advisory Database","source_url":"https://github.com/advisories/GHSA-mfxh-vp55-7gc6","source_modified_at":"2026-10-09T20:54:07Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"ecosystem":"composer","name":"contao/core-bundle"},"range":">= 5.4.0-RC1, < 5.7.12"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-107843","source_modified_at":"2026-10-13T17:08:23.664Z","fetched_at":"2026-10-23T18:45:31.882637Z","product":"contao","vendor":"contao","versions":[{"status":"affected","version":">= 4.1.0, < 5.3.50"},{"status":"affected","version":">= 5.4.0-RC1, < 5.7.12"}],"defaultStatus":null},{"source":"OSV","source_url":"https://osv.dev/vulnerability/GHSA-mfxh-vp55-7gc6","source_modified_at":"2026-10-09T21:00:10.232779369Z","fetched_at":"2026-10-23T18:48:36.087640Z","package":{"name":"contao/core-bundle","ecosystem":"Packagist","purl":"pkg:composer/contao/core-bundle"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.1.0"},{"fixed":"5.3.50"}]}],"versions":["4.1.0","4.1.1","4.1.2","4.1.3","4.10.0","4.10.0-RC1","4.10.0-RC2","4.10.0-RC3","4.10.0-RC4","4.10.1","4.10.2","4.10.3","4.10.4","4.10.5","4.10.6","4.10.7","4.11.0","4.11.0-RC1","4.11.0-RC2","4.11.1","4.11.2","4.11.3","4.11.4","4.11.5","4.11.6","4.11.7","4.11.8","4.11.9","4.12.0","4.12.0-RC1","4.12.0-RC2","4.12.0-RC3","4.12.1","4.12.2","4.12.3","4.12.4","4.12.5","4.12.6","4.12.7","4.13.0","4.13.0-RC1","4.13.0-RC2","4.13.0-RC3","4.13.1","4.13.10","4.13.11","4.13.12","4.13.13","4.13.14","4.13.15"]},{"source":"OSV","source_url":"https://osv.dev/vulnerability/GHSA-mfxh-vp55-7gc6","source_modified_at":"2026-10-09T21:00:10.232779369Z","fetched_at":"2026-10-23T18:48:36.087640Z","package":{"name":"contao/core-bundle","ecosystem":"Packagist","purl":"pkg:composer/contao/core-bundle"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.4.0-RC1"},{"fixed":"5.7.12"}]}],"versions":["5.4.0","5.4.0-RC1","5.4.0-RC2","5.4.0-RC3","5.4.0-RC4","5.4.1","5.4.10","5.4.11","5.4.12","5.4.13","5.4.14","5.4.2","5.4.3","5.4.4","5.4.5","5.4.6","5.4.7","5.4.8","5.4.9","5.5.0","5.5.0-RC1","5.5.0-RC2","5.5.0-RC3","5.5.0-RC4","5.5.1","5.5.10","5.5.11","5.5.12","5.5.13","5.5.14","5.5.15","5.5.16","5.5.2","5.5.3","5.5.4","5.5.5","5.5.6","5.5.7","5.5.8","5.5.9","5.6.0","5.6.0-RC1","5.6.0-RC2","5.6.0-RC3","5.6.1","5.6.10","5.6.11","5.6.2","5.6.3","5.6.4"]}],"fixed_versions":[{"source":"GitHub Advisory Database","source_url":"https://github.com/advisories/GHSA-mfxh-vp55-7gc6","source_modified_at":"2026-10-09T20:54:07Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"ecosystem":"composer","name":"contao/core-bundle"},"version":"5.3.50"},{"source":"GitHub Advisory Database","source_url":"https://github.com/advisories/GHSA-mfxh-vp55-7gc6","source_modified_at":"2026-10-09T20:54:07Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"ecosystem":"composer","name":"contao/core-bundle"},"version":"5.7.12"},{"source":"OSV","source_url":"https://osv.dev/vulnerability/GHSA-mfxh-vp55-7gc6","source_modified_at":"2026-10-09T21:00:10.232779369Z","fetched_at":"2026-10-23T18:48:36.087640Z","package":{"name":"contao/core-bundle","ecosystem":"Packagist","purl":"pkg:composer/contao/core-bundle"},"version":"5.3.50"},{"source":"OSV","source_url":"https://osv.dev/vulnerability/GHSA-mfxh-vp55-7gc6","source_modified_at":"2026-10-09T21:00:10.232779369Z","fetched_at":"2026-10-23T18:48:36.087640Z","package":{"name":"contao/core-bundle","ecosystem":"Packagist","purl":"pkg:composer/contao/core-bundle"},"version":"5.7.12"}],"cvss":5.3,"severity":"Medium","kev":{"listed":false},"epss":{"probability":0.00255,"percentile":0.16221,"score_date":"2026-10-23"},"published_at":"2026-10-09T19:21:32.011Z","modified_at":"2026-10-13T17:08:23.664Z","provenance":[{"source":"GitHub Advisory Database","url":"https://github.com/advisories/GHSA-mfxh-vp55-7gc6","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-09T20:54:07Z"},{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-107843","fetched_at":"2026-10-23T18:45:31.882637Z","source_modified_at":"2026-10-13T17:08:23.664Z"},{"source":"OSV","url":"https://osv.dev/vulnerability/GHSA-mfxh-vp55-7gc6","fetched_at":"2026-10-23T18:48:36.087640Z","source_modified_at":"2026-10-09T21:00:10.232779369Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-107843","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23"}],"sources":["GitHub Advisory Database","CVE List","OSV","EPSS"],"references":[{"source":"CVE List","url":"https://github.com/contao/contao/security/advisories/GHSA-mfxh-vp55-7gc6","tags":["x_refsource_CONFIRM"]},{"source":"CVE List","url":"https://github.com/contao/contao/commit/2ea6117f9049db7221679251cfc41e67d941a74b","tags":["x_refsource_MISC"]},{"source":"CVE List","url":"https://github.com/contao/contao/releases/tag/5.3.50","tags":["x_refsource_MISC"]},{"source":"CVE List","url":"https://github.com/contao/contao/releases/tag/5.7.12","tags":["x_refsource_MISC"]},{"url":"https://github.com/advisories/GHSA-mfxh-vp55-7gc6","source":"GitHub Advisory Database"}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","ssvc":{"exploitation":"none","automatable":"yes","technical_impact":"partial","assessed_at":"2026-10-13T17:08:09.326334Z"},"classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":"ecosystem","confidence":"heuristic","reviewed":false},"change_timestamp":"2026-10-13T17:08:23.664Z","content_hash":"72dfb53e7bd074bf47955e6fdceb28879d184c3fe9f7afef275dd40e1d075bff"}}