diff --git a/content/browser/interest_group/interest_group_priority_util.cc b/content/browser/interest_group/interest_group_priority_util.cc
index d4d40fd43022c1..038aeabef34b6d 100644
--- a/content/browser/interest_group/interest_group_priority_util.cc
+++ b/content/browser/interest_group/interest_group_priority_util.cc
@@ -4,6 +4,7 @@
 
 #include "content/browser/interest_group/interest_group_priority_util.h"
 
+#include <cmath>
 #include <optional>
 #include <string>
 
@@ -89,6 +90,13 @@ double CalculateInterestGroupPriority(
       break;
     }
   }
+  // Multiplying or summing large finite inputs can overflow to +/-Inf and
+  // then to NaN, which would later violate strict-weak-ordering in
+  // std::sort and corrupt heap memory in ApplySizeLimitAndSort(). Clamp to
+  // a safe value; the priority is only used for relative ordering.
+  if (!std::isfinite(caclulated_priority)) {
+    return 0;
+  }
   return caclulated_priority;
 }