CVE-2026-107843

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.

• CWE-204
• CWE-770

• 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
• https://github.com/contao/contao/security/advisories/GHSA-mfxh-vp55-7gc6

Published

Oct 9, 2026

Last Modified

Oct 9, 2026

Status

Received

• How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
• Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
• PR ReviewsPentest every pull request so vulnerable code is caught before it ships to production.
• AI Penetration TestingHow AI-driven penetration testing continuously covers your attack surface.

• CVE-2026-107837RIOT is an open-source microcontroller operating system desi…8.2
• CVE-2026-107838RIOT is an open-source microcontroller operating system desi…7.5
• CVE-2026-107839ageLANServer provides a cross-platform web server and launch…7.5
• CVE-2026-107840yopass is a service for securely sharing secrets, passwords,…7.5
• CVE-2026-107841pacioli provides least-privilege governance and a governed a…5.7
• CVE-2026-107842Contao is an Open Source CMS. From version 4.0.0 until 5.3.5…5.3
• CVE-2026-107844Contao is an Open Source CMS. From version 5.0.0 until 5.3.5…5.3
• CVE-2026-107845Contao is an Open Source CMS. From version 4.0.0 until 5.3.5…9.3
• CVE-2026-10786Improper access control in the ticketing integration setting…6.5
• CVE-2026-10787Missing authorization in the deleted user groups API in Devo…4.3
• CVE-2026-107885OpenPrinting CUPS through 2.4.20 contains a resource-exhaust…3.3
• CVE-2026-107886OpenPrinting CUPS before 2.4.20 contains a double-free in pr…2.3