BGP hijacking
BGP hijacking is the announcement of an IP prefix by a network that has no authority over it, causing traffic destined for the legitimate holder to be routed elsewhere. It is a failure of trust in the routing system rather than a software vulnerability: routers accept the announcement because the protocol was built to.
Two mechanics account for most incidents. Announcing a more specific prefix than the legitimate one, which wins because routing prefers the most specific match, and manipulating the path so a route appears shorter or more trustworthy than it is. A substantial share of events are configuration errors rather than attacks, and the effect on the victim is identical either way.
The consequence that matters beyond availability is certificate issuance. A certificate authority that validates domain control by contacting the domain over the network can be answered by whoever is currently receiving that traffic. That turns a routing event into a validly issued certificate for someone else’s name, which is the reason to say plainly that a domain validated certificate proves control of a name at a moment in time, not the identity of an organisation, and why it belongs in the same conversation as DNS hijacking and the wider public key infrastructure.
The defence is route origin validation using RPKI, where the holder of a prefix publishes which network is authorised to announce it and other networks reject announcements that contradict it. RPKI is the control, not another name for the attack. For most organisations this is outside the scope of an engagement and inside the scope of a supplier question: whether their transit providers and their content delivery provider validate route origins, and whether their own prefixes are signed.