CVE-2011-1429 in Mutt
Summary
by MITRE
Mutt does not verify that the smtps server hostname matches the domain name of the subject of an X.509 certificate, which allows man-in-the-middle attackers to spoof an SSL SMTP server via an arbitrary certificate, a different vulnerability than CVE-2009-3766.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 01/14/2025
The vulnerability identified as CVE-2011-1429 represents a critical security flaw in the Mutt email client that fundamentally compromises the integrity of secure email communications. This issue specifically affects the client's handling of SMTP over SSL connections where the application fails to perform proper hostname verification against the X.509 certificates presented by SMTP servers. The absence of this crucial validation mechanism creates a significant attack surface that enables malicious actors to execute successful man-in-the-middle attacks against email infrastructure.
The technical root cause of this vulnerability lies in Mutt's implementation of SSL/TLS certificate validation routines which neglect to verify that the hostname specified in the SMTP server connection matches the subject field of the presented X.509 certificate. This omission directly violates fundamental security principles outlined in industry standards such as CWE-295, which specifically addresses improper certificate validation. The flaw operates at the transport layer security validation level, where proper hostname matching should occur during the SSL handshake process to ensure that the client is communicating with the intended server rather than an impostor.
From an operational perspective, this vulnerability exposes users to severe security risks including unauthorized access to email communications, potential data interception, and the compromise of sensitive information transmitted through email channels. Attackers can exploit this weakness by presenting a valid certificate for a different domain, effectively allowing them to impersonate legitimate email servers and capture or manipulate email traffic. The impact extends beyond individual user accounts to potentially affect entire email infrastructure security, particularly in environments where Mutt is used for business communications or sensitive data transmission.
The security implications of CVE-2011-1429 align with tactics described in the MITRE ATT&CK framework under the 'Initial Access' and 'Credential Access' phases, where adversaries can establish persistent access through forged server identities. This vulnerability particularly affects organizations relying on email security for critical communications, as it undermines the trust model that SSL/TLS is designed to provide. The attack vector is particularly concerning because it does not require sophisticated techniques beyond standard certificate manipulation, making it accessible to threat actors with basic cryptographic knowledge.
Organizations and users should immediately implement mitigations including updating to patched versions of Mutt where hostname verification has been properly implemented, configuring explicit certificate validation policies, and considering alternative email clients with more robust security implementations. Network administrators should also deploy additional monitoring to detect unusual certificate usage patterns and consider implementing certificate pinning mechanisms where appropriate. The vulnerability serves as a reminder of the critical importance of proper SSL/TLS certificate validation in maintaining secure communications infrastructure and aligns with security best practices outlined in NIST SP 800-57 and other cryptographic standards that emphasize the necessity of certificate hostname validation to prevent man-in-the-middle attacks.