While IPv6 was standardized in the 90’s, only the last decade has seen a growth in its global adoption. In addition to dealing with IPv4 addresses exhaustion, IPv6 comes with a mechanism, called IPv6 Extension Header (IPv6 EH), allowing the protocol to be more flexible and extensible. In this paper, we investigate how IPv6 EHs are processed in the network. In particular, we focus on the survivability of IPv6 EHs, i.e., the fact that an IPv6 EH traverses the Internet and arrives unmodified at the destination. We first design experiments in a controlled environment, testing different IPv6 EHs and sizes on different routers from various vendors. Then, we confront our observations with several measurement campaigns between vantage points hosted by different Cloud Providers (CPs) around the world, and we compare them to the responses received from a survey of operators. Our results show that the survivability of IPv6 EHs is quite limited (around 50%) and is a consequence of operators’ policies, with some Autonomous Systems being responsible for most of the IPv6 EHs drops. Measurement tool and data collected are provided to the research community.