From 77bf4419e0465c7455eee2646b8e09ff2e38ad18 Mon Sep 17 00:00:00 2001
From: Uncle Stinky <uncle.stinky@ghostchain.io>
Date: Sat, 26 Sep 2026 14:30:22 +0300
Subject: [PATCH] prevent exploit via compute_arguments_hash bypass

Signed-off-by: Uncle Stinky <uncle.stinky@ghostchain.io>
---
 pallets/weaver/Cargo.toml   |  2 +-
 pallets/weaver/src/types.rs | 22 +++++++++-------------
 2 files changed, 10 insertions(+), 14 deletions(-)

diff --git a/pallets/weaver/Cargo.toml b/pallets/weaver/Cargo.toml
index f474738..3b72278 100644
--- a/pallets/weaver/Cargo.toml
+++ b/pallets/weaver/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "ghost-weaver"
-version = "0.0.14"
+version = "0.0.15"
 description = "Weaving a secure cryptographic tapestry across different external chains."
 license.workspace = true
 authors.workspace = true
diff --git a/pallets/weaver/src/types.rs b/pallets/weaver/src/types.rs
index dab7402..b9a2624 100644
--- a/pallets/weaver/src/types.rs
+++ b/pallets/weaver/src/types.rs
@@ -14,7 +14,6 @@ use ghost_helpers::{
     merkle_tree::verify_tree_proof,
     SubstrateBlake2Hasher, SubstrateKeccakHasher, UtxoSha2Hasher,
 };
-use ghost_traits::hashing::GhostHasher;
 
 use crate::{ExternalBlockNumber, ThreadId, WeavingSession};
 
@@ -350,8 +349,10 @@ where
 	{
         if EVM_MERKLE_DEPTH as usize != self.proof.len() { return None; }
 
+        let preimage_hash = self.get_preimage_hash(network_id)?;
+
         let proof_valid = verify_tree_proof::<SubstrateKeccakHasher, _>(
-            &self.get_preimage_slice(network_id).to_fixed_bytes(),
+            &preimage_hash.to_fixed_bytes(),
             self.proof.as_ref(),
             root_hash,
             self.proof_index,
@@ -362,22 +363,17 @@ where
         Some((self.receiver.clone(), self.amount))
     }
 
-    fn get_preimage_slice<NetworkId>(&self, network_id: NetworkId) -> H256
+    fn get_preimage_hash<NetworkId>(&self, network_id: NetworkId) -> Option<H256>
 	where
 		NetworkId: Copy + Clone + Eq + PartialEq + UniqueSaturatedInto<u64>,
 	{
         let slot_index_usize: usize = self.slot_index.unique_saturated_into();
-        let mut slot_values: Vec<H256> = self.slots.to_vec();
 
-        match slot_values.get_mut(slot_index_usize) {
-            Some(slot) => {
-                *slot = self.compute_arguments_hash(network_id);
-                cumulative_hash::<SubstrateKeccakHasher, _>(slot_values)
-            }
-            None => {
-                SubstrateKeccakHasher::empty()
-            }
-        }
+        self.slots.get(slot_index_usize)
+            .filter(|&&provided_hash| {
+                provided_hash == self.compute_arguments_hash(network_id)
+            })
+            .map(|_| cumulative_hash::<SubstrateKeccakHasher, _>(self.slots.iter()))
     }
 
     pub fn get_unique_key<NetworkId>(