Unexpected　port　disruptions,　caused　by　severe　congestion　or　geopolitical　conflicts,　can　lead　to　reassignment　of　shipping　flows　and　trigger　cascading　hazards　across　the　Global　Container　Shipping　Network　(GCSN),　with　far-reaching　socioeconomic　impacts.　Understanding　the　mechanisms　of　such　cascading　risk　propagation　requires　accurate　simulation　of　dynamic　flow　reassignment　and　the　development　of　a　tailored　diffusion　model　for　maritime　scenarios.　This　research　introduces　a　novel　cascading　modeling　framework　that　captures　port-level　dynamic　shipping　flow　reassignment　and　assesses　cascading　failure　diffusion　in　the　GCSN.　Using　massive　container　vessel　trajectory　data,　we　design　a　directed　and　weighted　GCSN,　identify　alternative　ports　for　disrupted　nodes　through　a　combination　of　network　topology　analysis　and　geographic　nearest-neighbor　search,　and　refine　port　selection　with　a　nonlinear　trajectory　cost　function　incorporating　maritime　distance,　vessel　load　differences,　and　port　size.　Cascading　failure　is　simulated　by　integrating　the　Motter-Lai　load-capacity　model　with　the　dynamic　reassignment　process,　and　three　maritime-specific　vulnerability　indicators　are　proposed　to　evaluate　network　resilience.　The　findings　show　that　limiting　port　loads　to　60　%　of　capacity　or　increasing　port　capacity　by　40　to　60　%　significantly　mitigates　cascading　risk.　It　also　appears　that　the　European　port　system　is　found　to　be　more　susceptible　to　cascading　disruptions　than　its　East　Asian　counterpart.　The　proposed　approach　provides　actionable　insights　and　risk　mitigation　strategies　for　enhancing　the　resilience　of　global　maritime　logistics　in　the　face　of　unexpected　disruptions.　©　2025　Elsevier　Ltd