Validator proof duplication bypasses consensus — AuditVault synthetic reduction

Source & credit. Reproduction of a public audit finding curated by AuditVault — the original finding: 55229-h-2-malicious-validators-will-bypass-consensus-threshold-req. Standalone Foundry PoC and full write-up: 55229-h-2-malicious-validators-will-bypass-consensus-threshold-req_exp in the evm-hack-registry mirror.

Vulnerability classes: vuln/bridge/missing-validation · vuln/bridge/replay

Reproduction: self-contained Foundry PoC with an offline synthetic contract. Full trace: output.txt.

AuditVault finding: 55229 · H-2: Malicious validators will bypass consensus threshold requirements affecting the integrity of the [[SEDA]] protocol's cross-chain data verification system

Key info#


Impact	HIGH — Validator proof duplication bypasses consensus
Protocol	SEDA Protocol
Finding	AuditVault #55229
Report	https://github.com/sherlock-audit/2024-12-seda-protocol-judging
Source	AuditVault finding
Compiler	`^0.8.24` (synthetic reduction)
Loss	Reduced invariant reproduced; no live funds moved
Attacker EOA	Configured synthetic caller
Attack contract	`Exploit`
Attack tx	Local Foundry `Exploit.attack()` call
Chain · block · date	Ethereum model · block 1 · synthetic
Vulnerable contract	Local synthetic vulnerable contract in `test/`
Bug class	See vulnerability-class tags above

TL;DR#

This bug report discusses a critical security issue with the SEDA protocol's cross-chain data verification system. The issue was discovered by a group of researchers and could potentially allow malicious validators to bypass the consensus mechanism and manipulate data on the network. The root cause of the issue was found in the code that accumulates validator voting power without checking for duplicate entries. This allows malicious validators to artificially inflate their voting power and unilaterally approve batches. The report also outlines the necessary pre-conditions for the attack and provides a proof of concept demonstrating how validators with varying levels of power can exploit the vulnerability. The report concludes with a proposed fix that involves tracking duplicate validators to prevent them from being counted more than once. The protocol team has already implemented this fi

Background#

The upstream report is a Solidity finding. This page keeps the vulnerable statement and demonstrates its security consequence in a small, deterministic EVM model; no live RPC or external dependencies are required.

The vulnerable code#

SOLIDITY

// The exact vulnerable pattern is retained in test/55229-h-2-malicious-validators-will-bypass-consensus-threshold-req.sol.
// @> see the marked statement in the synthetic reduction

Root cause#

The caller-controlled input or stale state is trusted before the required uniqueness, bounds, authorization, accounting, or reentrancy invariant is enforced. The marked line in the synthetic contract intentionally preserves that ordering so the assertion is executable.

Preconditions#

The vulnerable contract is deployed with the state described by the report.
The attacker can reach the affected entry point (or submit the report's crafted input).

Attack walkthrough#

Exploit.run() initializes the minimal state from the report.
The marked vulnerable operation executes without its required check.
The contract records the resulting invariant violation and emits a Proof event.
The test asserts the harm; the passing trace is recorded at output.txt:4.

Diagrams#

flowchart TD A[Attacker supplies crafted input] --> B[Vulnerable operation] B --> C{Missing invariant check} C --> D[Security impact demonstrated]

sequenceDiagram participant A as Attacker participant V as Vulnerable contract participant S as State A->>V: invoke affected entry point V->>S: apply unchecked update S-->>A: harm is observable

Remediation#

Apply the invariant before mutating state: accrue interest before adding principal; reject duplicate signers; use checked casts and bounded lengths; validate token/target/DAO identities; use nonReentrant; enforce slippage and fee equality; and validate the canonical authority or ownership relationship described by the report.

How to reproduce#

BASH

cd evm-hack-registry/55229-h-2-malicious-validators-will-bypass-consensus-threshold-req_exp
forge test -vvvvv

The test is offline and uses only the shared forge-std library. The corresponding Playground bundle is generated from scripts/poc-configs/55229-h-2-malicious-validators-will-bypass-consensus-threshold-req.mjs.

Sources#

Reference: https://github.com/sherlock-audit/2024-12-seda-protocol-judging

Sources & further analysis#

Reproductions & code

Standalone PoC + full trace: 55229-h-2-malicious-validators-will-bypass-consensus-threshold-req_exp (evm-hack-registry mirror).
AuditVault finding: 55229-h-2-malicious-validators-will-bypass-consensus-threshold-req.

Alerts & third-party analyses

Web3Sec X hacked database: search.
Rekt leaderboard: search.
Solodit incident search: search.

These dashboards index community alerts tweets, post-mortems, and independent write-ups. Reach them through the protocol name above to cross-check this reproduction against other analyses.

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