CVE-2026-4208
Published: 17 March 2026
Summary
CVE-2026-4208 is a high-severity Authorization Bypass Through User-Controlled Key (CWE-639) vulnerability in Mrsilaz Mfa Mail. Its CVSS base score is 7.7 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 16.8th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 IA-5 (Authenticator Management) and SI-2 (Flaw Remediation).
Deeper analysis
CVE-2026-4208 is a vulnerability in a TYPO3 extension that fails to properly reset the generated MFA code after successful authentication. This flaw enables a possible MFA bypass for future login attempts by submitting an empty string as the MFA code to the extension's MFA provider. The issue carries a CVSS v3.1 base score of 8.8 (AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H) and maps to CWE-639 (Authorization Bypass Through User-Controlled Key). It was published on 2026-03-17.
The vulnerability can be exploited remotely by an attacker with low privileges, such as an authenticated user requiring minimal privileges (PR:L), with low attack complexity and no user interaction. By leveraging the failure to reset the MFA code post-authentication, the attacker submits an empty string during subsequent login attempts to bypass MFA validation, potentially resulting in high impacts to confidentiality, integrity, and availability.
Mitigation details are provided in the TYPO3 security advisory at https://typo3.org/security/advisory/typo3-ext-sa-2026-007.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-12554
Vulnerability details
The extension fails to properly reset the generated MFA code after successful authentication. This leads to a possible MFA bypass for future login attempts by providing an empty string as MFA code to the extensions MFA provider.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Vuln in public-facing TYPO3 CMS extension directly enables remote MFA bypass via empty code submission after failed reset (CWE-639 authz flaw), facilitating T1190 exploitation, T1556.006 MFA modification/bypass for access, and T1078 abuse of valid accounts.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
IA-5 mandates proper management, refresh, and invalidation of authenticators like MFA codes after successful authentication, directly preventing reuse or bypass via unreset states and empty strings.
SI-10 requires validation of inputs such as MFA codes, rejecting empty or invalid values to block bypass attempts exploiting improper code handling.
SI-2 ensures timely identification, reporting, and patching of flaws like this MFA reset failure, preventing exploitation of the vulnerability.