A vulnerability (just patched) in the random number generator used in the Kaspersky Password Manager resulted in easily guessable passwords:
The password generator included in Kaspersky Password Manager had several problems. The most critical one is that it used a PRNG not suited for cryptographic purposes. Its single source of entropy was the current time. All the passwords it created could be bruteforced in seconds. This article explains how to securely generate passwords, why Kaspersky Password Manager failed, and how to exploit this flaw. It also provides a proof of concept to test if your version is vulnerable.
The product has been updated and its newest versions aren’t affected by this issue.
Stupid programming mistake, or intentional backdoor? We don’t know.
More generally: generating random numbers is hard. I recommend my own algorithm: Fortuna. I also recommend my own password manager: Password Safe.
EDITED TO ADD: Commentary from Matthew Green.