nginx 0.5.6 through 1.7.4, when using the same shared ssl_session_cache or ssl_session_ticket_key for multiple servers, can reuse a cached SSL session for an unrelated context, which allows remote attackers with certain privileges to conduct "virtual host confusion" attacks.

References

• https://nvd.nist.gov/vuln/detail/CVE-2014-3616
• https://mailman.nginx.org/pipermail/nginx-announce/2014/000147.html
• https://www.debian.org/security/2014/dsa-3029