A 40-year-old male farmer presents with irregular fever for 3 days, accompanied by headache, low back pain, and blurred vision. Physical examination shows facial and upper chest congestion, conjunctival edema, petechiae, and scattered pin-sized petechiae in the axilla and back. Blood pressure is 90/60 mmHg. Due to similar cases in the village, he is transferred to a city hospital with a suspected diagnosis of epidemic hemorrhagic fever (febrile phase). The primary cause of bleeding at this stage is: