CVE-2022-24732 is a vulnerability identified in the open-source Maddy Mail Server, an SMTP-compatible email server developed by foxcpp. The issue affects versions prior to 0.5.4 and relates to insufficient session expiration when authenticating users via PAM (Pluggable Authentication Modules). Specifically, Maddy versions before 0.5.4 do not enforce password expiry or account expiry checks during authentication. This means that even if a user's password or account has expired according to PAM policies, the Maddy server will still allow authentication, effectively bypassing these security controls. The vulnerability is categorized under CWE-613 (Insufficient Session Expiration) and CWE-324 (Use of a Key Past Its Expiration Date), indicating that session or credential validity is not properly enforced. The lack of session expiration or account expiry enforcement can lead to prolonged unauthorized access if credentials or accounts are compromised or should otherwise be disabled. Although no known exploits have been reported in the wild, the vulnerability poses a risk of unauthorized access to mail services, potentially allowing attackers to send or receive emails under expired or revoked accounts. This could facilitate further attacks such as phishing, data exfiltration, or lateral movement within a network. The vulnerability does not require user interaction beyond authentication and affects all Maddy Mail Server deployments running versions prior to 0.5.4 that rely on PAM for authentication. Users are advised to upgrade to version 0.5.4 or later where this issue is fixed. For those unable to upgrade, manual removal of expired accounts using existing filtering mechanisms is recommended to mitigate risk.

For European organizations, the impact of this vulnerability can be significant, especially for entities relying on Maddy Mail Server for internal or external email communications. Unauthorized access due to insufficient session expiration can lead to compromise of sensitive communications, exposure of confidential data, and potential disruption of email services. This risk is heightened in sectors with strict data protection regulations such as GDPR, where unauthorized access to personal data can result in legal and financial penalties. Additionally, compromised email accounts can be leveraged for spear-phishing campaigns targeting employees or partners, increasing the risk of broader network compromise. Organizations in critical infrastructure, finance, healthcare, and government sectors are particularly vulnerable due to the sensitive nature of their communications and the potential for cascading effects from email compromise. The lack of password or account expiry enforcement may also undermine internal security policies and compliance requirements, leading to audit failures and reputational damage. While no active exploitation has been reported, the vulnerability's presence in open-source software used in diverse environments means that attackers could develop exploits if motivated, especially targeting organizations with less frequent patching cycles or limited security monitoring.

The primary mitigation is to upgrade Maddy Mail Server to version 0.5.4 or later, where the vulnerability has been addressed by implementing proper password and account expiry checks during PAM authentication. For organizations unable to upgrade immediately, it is critical to implement manual controls to remove or disable expired accounts using existing filtering or account management mechanisms within Maddy. Additionally, organizations should audit their PAM configurations and ensure that account and password expiry policies are correctly enforced at the system level. Monitoring authentication logs for unusual or repeated access attempts from expired accounts can help detect potential misuse. Implementing multi-factor authentication (MFA) where possible can reduce the risk of unauthorized access even if expired credentials are improperly accepted. Network segmentation and strict access controls around mail servers can limit the impact of any compromise. Regular security assessments and patch management processes should be enforced to prevent prolonged exposure to such vulnerabilities. Finally, organizations should educate administrators and users about the importance of timely updates and account lifecycle management to maintain security hygiene.