Cisco software contains a vulnerability that could allow an unauthenticated, remote attacker to access sensitive information on a targeted system.
The vulnerability is in the encryption library used by the vulnerable software. This library allows a portion of an encrypted packet to be sent unencrypted in the following packet. The vulnerability occurs only when IP Security (IPsec) is used, as with VPN environments. If an unauthenticated, remote attacker could access an encrypted session, the attacker could obtain unencrypted packets that would contain information. The attacker may benefit from this information and possibly launch further attacks.
Cisco has confirmed the vulnerability and released software updates.
To exploit this vulnerability, an attacker must have access to a specific combination of hardware modules and encryption libraries in a targeted device. In many cases, this access may require the attacker to have access to internal, trusted networks. These access requirements may limit the potential of a successful exploit.
A successful exploit requires an attacker to have access to the encrypted packet stream. In addition, the attacker cannot control which packets or what portion of the packet will be subject to this vulnerability. However, there is a potential that the decrypted portion of a packet may contain sensitive information.