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Reproduced Exploit

carryVoteForward() enables double voting

Jan 1970•Other•untagged•2 min read

Chain

Other

Category

untagged

Date

Jan 1970

Source

DeFiHackLabs

PoC & write-upPoC for your local evm-hack-analyzerDeFiHackLabs PoCs

EVM Playground

Source-level debugger — step opcodes and Solidity in sync

evm-hack-analyzer

The attack is replayed in an in-browser EVM preloaded with the exact dumped fork state. The execution tree shows every call; step by Solidity line or by opcode across all depths — source, Stack, Memory, Storage, Balances (native / ERC-20 / NFT), Transient storage and Return value stay in sync. Click a tree node, opcode, or source line to jump. No backend, no live RPC.

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Source & credit. Exploit reproduction, trace data, and analysis adapted from DeFiHackLabs by SunWeb3Sec — an open registry of reproduced on-chain exploits. The historical source/toolchain is unavailable; this entry is documentation only and claims no executable Forge PoC. DeFiHackLabs PoC directory: src/test.

Vulnerability classes: vuln/logic

Reproduction: a faithful minimal reproduction of the vulnerable finding — the vulnerable code is reproduced verbatim (marked @>) with faithful minimal doubles; local deploy, no fork.

Root cause#

carryVoteForward casts votes for the next period but never sets voted[tokenId]=true, so checkPeriodVoted stays false and the notVoted guard is bypassed - the attacker splits the still-unvoted NFT and votes again, double-counting 100e18 of voting weight.

SOLIDITY
        // deposit votes to next period
        _vote(nextPeriod, _tokenId, _poolList, _weightList); // @> VULN (this line)

Why it's exploitable here#

carryVoteForward casts votes for the next period but never sets voted[tokenId]=true, so checkPeriodVoted stays false and the notVoted guard is bypassed - the attacker splits the still-unvoted NFT and votes again, double-counting 100e18 of voting weight.

Attack path#

flowchart TD S0["Step"] S1["Step"] S2["Step"] S3["Step"] S4["Step"] H["carryVoteForward casts votes for the next period but never s"] S0 --> S1 S1 --> S2 S2 --> S3 S3 --> S4 S4 --> H

Marked-line walkthrough (Playground)#

The EVM Playground pins each step to the exact executed source line in 0x671d353a77…:

  1. L46 — Step: Executes uint256 public currentPeriod;
  2. L55 — Step: Executes for (uint256 i; i < pools.length; i++) {
  3. L64 — Step: Executes function vote(uint256 _tokenId, address[] calldata pools, uint256[] calldata weights) external {
  4. L71 — Step: Executes function seedFromPeriod(uint256 _fromPeriod, uint256 _tokenId, address pool, uint256 weight) external {
  5. L79 — Step: Executes Period storage ps = period[_fromPeriod];
  6. L87 — Step: Executes address _gauge = gauge[_poolList[i]];
  7. L92 — Vulnerable line: Executes _vote(nextPeriod, _tokenId, _poolList, _weightList);

PoC#

Registry (Foundry, local deploy — verbatim vulnerable source + harm-asserting test):

BASH
cd 61950-c-01-carryvoteforward-enables-double-voting-pashov-audit-gro_exp
forge test -vvv

The browser Playground replays the same synthetic opcode-for-opcode and measures the harm. Both gates are green (registry forge test PASS + Playground _verify-poc VERDICT: PASS).

Sources & further analysis#

Reproductions & code

  • No executable Forge reproduction is claimed; the historical source/toolchain was unavailable for this finding.
  • Upstream DeFiHackLabs PoC directory: src/test.

Alerts & third-party analyses

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.