CVE-2022-26562 in Kopano
Summary
by MITRE • 04/02/2022
An issue in provider/libserver/ECKrbAuth.cpp of Kopano-Core v11.0.2.51 contains an issue which allows attackers to authenticate even if the user account or password is expired.
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Analysis
by VulDB Data Team • 05/10/2026
The vulnerability identified as CVE-2022-26562 resides within the Kopano-Core v11.0.2.51 software suite, specifically in the provider/libserver/ECKrbAuth.cpp component that handles Kerberos authentication. This flaw represents a critical security weakness that undermines the integrity of the authentication process by permitting unauthorized access even when user credentials have expired or been disabled. The issue stems from improper validation of account status during the Kerberos authentication workflow, creating a persistent backdoor that attackers can exploit to maintain access to systems despite legitimate account expiration policies.
The technical implementation flaw manifests in the Kerberos authentication module where the system fails to properly verify account expiration status before granting access privileges. This vulnerability operates at the authentication layer and directly impacts the security principle of least privilege by allowing expired accounts to continue functioning within the system. The flaw essentially bypasses the normal account validation checks that should occur during the Kerberos ticket validation process, enabling attackers to leverage compromised or expired credentials for continued unauthorized access. This type of vulnerability aligns with CWE-287 which addresses improper authentication mechanisms and represents a significant deviation from established security protocols.
The operational impact of this vulnerability extends beyond simple unauthorized access as it creates a persistent threat vector that can remain undetected for extended periods. Attackers can exploit this weakness to maintain long-term presence within networks, potentially leading to data exfiltration, lateral movement, and privilege escalation attacks. The vulnerability affects organizations that rely on Kopano for email and collaboration services, particularly those with strict account expiration policies that are now effectively circumvented. This weakness can be particularly dangerous in environments where account lifecycle management is critical for security compliance and where expired accounts should be immediately revoked.
Organizations should immediately implement mitigations including patching to the latest version of Kopano-Core that addresses this vulnerability, implementing additional authentication layers, and conducting thorough security audits of all Kerberos-enabled services. The fix should involve proper account status validation within the Kerberos authentication flow and comprehensive testing to ensure that expired accounts cannot authenticate successfully. Security teams should also monitor authentication logs for unusual patterns that might indicate exploitation attempts and consider implementing additional monitoring controls around account expiration events. This vulnerability demonstrates the importance of maintaining up-to-date security patches and the critical nature of proper authentication validation in preventing persistent security threats.