Cisco has identified a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service condition. The vulnerability is due to improper processing of malformed IPv6 packets carrying extension headers. Cisco Network Convergence System 6000 (NCS 6000) and Cisco Carrier Routing System X (CRS-X) running an affected version of Cisco IOS XR Software are affected by this vulnerability.
Users and administrators are encouraged to review the Cisco Advisory (link is external) and apply the necessary updates.
DNSBLs and RBLs are generally used on mail servers to reject or flag messages sent from sites that have been Blacklisted. If your mail server has been added to the DNSBL’s database, emails sent are likely rejected or identified as SPAM.
Our IP Reputation Protection System queries major DNS-based Blackhole List databases and SenderBase which is one of the world’s largest email and web traffic monitoring network, and process these results to send alerts to our support team to take immediate action. We help the customer to identify the root cause, contacting the various DNSBL agency to request removal and mitigate the impact on emails returned to sender due to a blacklist.
If the event your mail server has been blacklisted, we usually take less than an hour to restore your mail service with IP Reputation Protection.