John Noh, a Cisco spokesman, said the password reset, which was initiated Monday after testing the vulnerability's veracity, was a precautionary measure to ensure users' safety.
He added the company doesn't believe any sensitive information was compromised.
Noh wouldn't say how many registered users the site hosts but said the vulnerability affected employees, business partners and third-party users. He said the company has reset the passwords for everyone, but is still in the process of resetting them for third-party users.
He declined to comment on the details of the vulnerability, but said the security firm that tipped them off in the first place did not want its name publicized.