Title: libESMTP X.509 Certificate 'match_component()' Domain Validation Security Bypass Vulnerability
Severity: CRITICAL
Description:
libESMTP is an SMTP (Simple Mail Transport Protocol) client and library. It includes support for SSL.
libESMTP is prone to a security-bypass vulnerability because it fails to properly validate domains against the Common Name field of an X.509 certificate. Specifically, the library may match a domain with a common name that contains the domain as a prefix. This issue affects the 'match_component()' function in the 'smtp-tls.c' source code file.
Successfully exploiting this issue allows attackers to perform man-in-the-middle attacks or impersonate trusted servers, which will aid in further attacks.
libESMTP 1.0.3 is vulnerable; other versions may also be affected.
Affected Products:
- libesmtp libesmtp 1.0.3
References:
- Martin Lambers: #311191 - libesmtp5: Flaw in TLS certificate hostname matching code
- libESMTP: libESMTP Homepage
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