ntopng through 6.6 is vulnerable to Predictable Session Identifier which can lead to Session Hijacking. HTTP session identifiers in src/HTTPserver.cpp use weak time-seeded pseudo-randomness during session creation. As a result, fresh authenticated logins can receive deterministic or colliding session cookies under attacker-controlled timing.
An issue was discovered in ntopng 3.4 before 3.4.180617. The PRNG involved in the generation of session IDs is not seeded at program startup. This results in deterministic session IDs being allocated for active user sessions. An attacker with foreknowledge of the operating system and standard library in use by the host running the service and the username of the user whose session they're targeting can abuse the deterministic random number generation in order to hijack the user's session, thus escalating their access.