From 5590e1430b3986eaef7bb93759afe7ff6b1d8191 Mon Sep 17 00:00:00 2001
From: Cardinal <adriadrop@gmail.com>
Date: Fri, 22 May 2026 12:46:16 +0200
Subject: [PATCH] fix(stamp): cast before min initial balance multiply

Cast minimumValidityBlocks and lastPrice to uint256 before multiplying
so minimumInitialBalancePerChunk cannot silently overflow in uint64 space.
---
 src/PostageStamp.sol | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/PostageStamp.sol b/src/PostageStamp.sol
index 00cdaa3f..23e4114e 100644
--- a/src/PostageStamp.sol
+++ b/src/PostageStamp.sol
@@ -566,7 +566,8 @@ contract PostageStamp is AccessControl, Pausable {
     }
 
     function minimumInitialBalancePerChunk() public view returns (uint256) {
-        return minimumValidityBlocks * lastPrice;
+        // Cast to uint256 before multiplying to avoid uint64 overflow.
+        return uint256(minimumValidityBlocks) * uint256(lastPrice);
     }
 
     /**