Secure Web Gateways (SWGs) are cloud-based SSL-intercepting proxies and an important component of enterprise Secure Access Service Edge (SASE) or Security Service Edge (SSE) solutions. SWGs ensure secure web access for enterprise users by doing malware protection, threat prevention, URL filtering, and content inspection of sensitive data, among other critical security measures. Our research indicates that in today's world of complex web applications and protocols, SWGs often fail to deliver on their promise. We will demonstrate a new class of attacks: “Last Mile Reassembly Attacks,” which, as of this writing, can bypass every SWG in the Gartner Magic Quadrant for SASE and SSE - this includes the largest public market cybersecurity companies in the world. Additionally, we will release an open-source attack toolkit for researchers and red teams to test these attacks on their security solutions and better understand their security exposure.