We examine how upstream technology vulnerability affects downstream firms' reliance on supply chain relationships and their subsequent strategic responses. Using patent litigation as an idiosyncratic shock to technology vulnerability, we find that upstream patent litigation reduces downstream supply chain reliance by 6.46% in the following year (fragility). We identify three underlying mechanisms: legal risks associated with technology, delivery uncertainties, and reputation risks driven by market pressures. Our results remain robust when exploiting the staggered adoption of the U.S. anti-troll laws as a quasi-natural experiment. Moreover, we find that when upstream technology supply is disrupted, downstream firms shift toward in-house development. By increasing R&D investments and recruiting external inventors, these affected customer firms enhance their innovation capabilities, especially in the disrupted technological domains (flexibility). This enables them to better integrate the technological supply chain and achieve greater product diversification.