offlineimap before 6.3.4 added support for SSL server certificate validation but it is still possible to use SSL v2 protocol, which is a flawed protocol with multiple security deficiencies.
CVSS 3.1CRITICAL 9.8·Network·No auth·No interaction·EPSS 0.01033·Published 2019-11-13·Fixed in 6.3.4CWE-295
offlineimap before 6.3.2 does not check for SSL server certificate validation when "ssl = yes" option is specified which can allow man-in-the-middle attacks.
CVSS 3.1MEDIUM 5.9·Network·No auth·No interaction·EPSS 0.00626·Published 2019-11-13·Fixed in 6.3.2CWE-295