CVE-2026-40878 Scanner

Mailcow-dockerized is a comprehensive mail server suite used extensively by organizations for managing email solutions through a docker-based environment. It supports various mail-related protocols like SMTP, IMAP, and POP3, providing features like spam protection, calendar integration, and contact management. Systems administrators and email service providers utilize Mailcow for its ease of deployment and robust feature set, allowing seamless integration with existing IT infrastructure. It serves as a reliable platform for SME businesses, educational institutions, and any organization requiring a secure and flexible email system. The suite is adaptable to varied server environments, offering detailed controls over each aspect of the mail server and related services. It provides a collaborative and highly configurable email management solution desired by IT departments aiming for efficiency and reliability.

Href Link Injection in Mailcow-dockerized can lead to severe consequences, primarily affecting email security and user data integrity. This vulnerability involves the injection of malicious scripts or URLs into href links and JavaScript on the login page. Attackers can exploit this flaw to manipulate parameters, breaking JavaScript logic and enabling phishing schemes. The vulnerability opens doors to unauthorized access and client-side script manipulation, leading to potential data exposure and security breaches. It targets functionalities connected to the user interface, affecting session management and authentication processes. By exploiting this weakness, attackers can create misleading redirects or execute scripts in a victim's session without their knowledge.

The technical mechanism of the Href Link Injection involves manipulating the REQUEST_URI reflected in mailcow's JavaScript and links on the login page. This weak spot allows an attacker to introduce additional parameters via specially crafted URLs that the application's scripts interpret and execute. Attackers may utilize backslashes and other special characters to hinder normal function, thus corrupting JavaScript logic. For instance, they might target session management features, like CSRF handler disruption or DoS of authentication modules such as FIDO2/WebAuthn. Critical parts of the mailcow-dockerized operation, such as login authentication, can suffer interruptions, leading to broader security risks and operational downtimes.

If exploited, the Href Link Injection vulnerability could enable phishing attacks by redirecting users to malicious sites designed to harvest credentials. It also poses the risk of DoS attacks against key authentication components, potentially affecting server availability. The manipulation of JavaScript logic could create backdoors or chinks in the security armor of the application, making sensitive user information susceptible to unauthorized access. Such vulnerabilities, when linked with other systemic weaknesses, could cause multi-vector attacks, amplifying the complexity and severity of security breaches. The malfunction of security protocols may further allow attackers to sustain access to the compromised system or escalate privileges within it.

REFERENCES

• https://github.com/mailcow/mailcow-dockerized/security/advisories/GHSA-xv9r-j862-5hqf
• https://github.com/mailcow/mailcow-dockerized
• https://nvd.nist.gov/vuln/detail/CVE-2026-40878