A vulnerability in Dovecot could allow an authenticated, remote attacker to impersonate other users on a targeted system.
The vulnerability exists because Dovecot incorrectly handles valid, trusted client certificates. An attacker who has access to a trusted SSL certificate with an empty username field could exploit this vulnerability to log in as another user on the targeted system. A successful exploit could be used to conduct further attacks.
Proof-of-concept (PoC) code that demonstrates an exploit of this vulnerability is publicly available.
Dovecot has confirmed the vulnerability and released software updates.
To exploit this vulnerability, the attacker must have user-level access to the targeted system. This access requirement could reduce the likelihood of a successful exploit.
Administrators are advised to apply the appropriate updates.
Administrators are advised to allow only trusted users to have network access.
Administrators are advised to run both firewall and antivirus applications to minimize the potential of inbound and outbound threats.
Administrators may consider using IP-based access control lists (ACLs) to allow only trusted systems to access the affected systems.
Administrators can help protect affected systems from external attacks by using a solid firewall strategy.
Administrators are advised to monitor affected systems.
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Cisco Multivendor Vulnerability Alerts respond to vulnerabilities identified in third-party vendors' products. These alerts contain information compiled from diverse sources and provide comprehensive technical descriptions, objective analytical assessments, workarounds and practical safeguards, and links to vendor advisories and patches.