From 550ca91b179493e5c0394ee644efed3deefb890e Mon Sep 17 00:00:00 2001
From: Sina M <1591639+s1na@users.noreply.github.com>
Date: Tue, 17 Feb 2026 15:42:48 +0100
Subject: [PATCH] consensus/misc: hardening header verification (#33860)

Defensively check parent's base fee before using it for calculations.
---
 consensus/misc/eip1559/eip1559.go | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/consensus/misc/eip1559/eip1559.go b/consensus/misc/eip1559/eip1559.go
index a90bd744b2..9a4cd320a8 100644
--- a/consensus/misc/eip1559/eip1559.go
+++ b/consensus/misc/eip1559/eip1559.go
@@ -43,6 +43,10 @@ func VerifyEIP1559Header(config *params.ChainConfig, parent, header *types.Heade
 	if header.BaseFee == nil {
 		return errors.New("header is missing baseFee")
 	}
+	// Verify the parent header is not malformed
+	if config.IsLondon(parent.Number) && parent.BaseFee == nil {
+		return errors.New("parent header is missing baseFee")
+	}
 	// Verify the baseFee is correct based on the parent header.
 	expectedBaseFee := CalcBaseFee(config, parent)
 	if header.BaseFee.Cmp(expectedBaseFee) != 0 {