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.

CVSS v3 5.3 MEDIUM

5.3^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 3.9 / Impact : 1.4

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact LOW

Integrity Impact NONE

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
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

Configurations

No configuration.

History

09 Oct 2026, 20:17

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-10-09 20:17

Updated : 2026-10-16 17:17

NVD link : CVE-2026-107843

Mitre link : CVE-2026-107843

CVE.ORG link : CVE-2026-107843

JSON object : View

Products Affected

No product.

CWE

CWE-204

Observable Response Discrepancy

CWE-770

Allocation of Resources Without Limits or Throttling

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