From dfc20332c1c298d05c52e4d05db51d83b80fe4de Mon Sep 17 00:00:00 2001
From: samsamtrum <pytynguyen@gmail.com>
Date: Tue, 2 Jun 2026 00:58:10 +0700
Subject: [PATCH] fix connect chain id normalization

---
 packages/connect/src/utils/helpers.test.ts | 21 ++++++++++++++++++
 packages/connect/src/utils/helpers.ts      | 25 ++++++++++++++++++----
 2 files changed, 42 insertions(+), 4 deletions(-)
 create mode 100644 packages/connect/src/utils/helpers.test.ts

diff --git a/packages/connect/src/utils/helpers.test.ts b/packages/connect/src/utils/helpers.test.ts
new file mode 100644
index 000000000..7c5e5ea78
--- /dev/null
+++ b/packages/connect/src/utils/helpers.test.ts
@@ -0,0 +1,21 @@
+import { describe, expect, it } from 'vitest'
+
+import { normalizeChainId } from './helpers'
+
+describe('normalizeChainId', () => {
+  it('normalizes supported chain id values', () => {
+    expect(normalizeChainId(1)).toBe(1)
+    expect(normalizeChainId(1n)).toBe(1)
+    expect(normalizeChainId('1')).toBe(1)
+    expect(normalizeChainId('0x1')).toBe(1)
+    expect(normalizeChainId({ chainId: '0x2105' })).toBe(8453)
+  })
+
+  it('rejects invalid chain id values', () => {
+    expect(() => normalizeChainId('1abc')).toThrow('Invalid chain id')
+    expect(() => normalizeChainId('abc')).toThrow('Invalid chain id')
+    expect(() => normalizeChainId('0x')).toThrow('Invalid chain id')
+    expect(() => normalizeChainId(Number.NaN)).toThrow('Invalid chain id')
+    expect(() => normalizeChainId(BigInt(Number.MAX_SAFE_INTEGER) + 1n)).toThrow('Invalid chain id')
+  })
+})
diff --git a/packages/connect/src/utils/helpers.ts b/packages/connect/src/utils/helpers.ts
index 1c7ab011c..46d5664c4 100644
--- a/packages/connect/src/utils/helpers.ts
+++ b/packages/connect/src/utils/helpers.ts
@@ -138,13 +138,30 @@ export const normalizeChainId = (chainId: string | number | bigint | { chainId:
   if (typeof chainId === 'object') {
     return normalizeChainId(chainId.chainId)
   }
+
+  let normalizedChainId: number
+
   if (typeof chainId === 'string') {
-    return Number.parseInt(chainId, chainId.trim().substring(0, 2) === '0x' ? 16 : 10)
+    const trimmed = chainId.trim()
+    const isHex = trimmed.startsWith('0x')
+    if (isHex ? !/^0x[\da-f]+$/iu.test(trimmed) : !/^\d+$/u.test(trimmed)) {
+      throw new Error(`Invalid chain id: ${chainId}`)
+    }
+    normalizedChainId = Number.parseInt(trimmed, isHex ? 16 : 10)
+  } else if (typeof chainId === 'bigint') {
+    if (chainId < 0n || chainId > BigInt(Number.MAX_SAFE_INTEGER)) {
+      throw new Error(`Invalid chain id: ${chainId.toString()}`)
+    }
+    normalizedChainId = Number(chainId)
+  } else {
+    normalizedChainId = chainId
   }
-  if (typeof chainId === 'bigint') {
-    return Number(chainId)
+
+  if (!Number.isSafeInteger(normalizedChainId) || normalizedChainId < 0) {
+    throw new Error(`Invalid chain id: ${chainId.toString()}`)
   }
-  return chainId
+
+  return normalizedChainId
 }
 
 export const isSequenceUrl = (url?: string): url is string => {