Notional Finance: Curve-gauge LP stakers receive 0 accrued CRV on exit because _unstakeLpTokens calls withdr

Source & credit. Reproduction of a public audit finding curated by AuditVault — the original finding: 63525-inability-to-claim-rewards-from-the-curve-gauge-mixbytes-non. Standalone Foundry PoC and full write-up: 63525-inability-to-claim-rewards-from-the-curve-gauge-mixbytes-non_exp in the evm-hack-registry mirror.

Vulnerability classes: vuln/locked-funds · vuln/reward-accounting

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

Root cause#

Curve-gauge LP stakers receive 0 accrued CRV on exit because _unstakeLpTokens calls withdraw(poolClaim) without the _claim_rewards flag (defaults False) and no reward-manager claim path exists, so 1000 CRV stays locked in the gauge, undelivered.

SOLIDITY

            bool success = IConvexRewardPool(CONVEX_REWARD_POOL).withdrawAndUnwrap(poolClaim, false);
            require(success);
        } else {
            ICurveGauge(CURVE_GAUGE).withdraw(poolClaim); // @> no _claim_rewards flag (defaults False) & no reward-manager claim path -> accrued CRV never delivered on unstake
        }
    }

Why it's exploitable here#

Attack path#

flowchart TD S0["Convex path withdraws without claim"] S1["Fall through to Curve gauge branch"] S2["Withdraw without _claim_rewards flag"] S3["Gauge deposit interface"] S4["Two-arg withdraw exists in interface"] H["Curve-gauge LP stakers receive 0 accrued CRV on exit because _unstakeL"] 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 0xe3a787a4e4…:

L190 — Convex path withdraws without claim: The Convex branch calls withdrawAndUnwrap(poolClaim, false), unwrapping the LP but passing false so rewards aren't claimed here either.
L192 — Fall through to Curve gauge branch: Setup: the else selects the Curve gauge exit path taken when the position is staked directly in the gauge.
L193 — Withdraw without _claim_rewards flag: Root cause: calls single-arg withdraw(poolClaim); _claim_rewards defaults False, so accrued CRV is never pulled and stays stuck in the gauge.
L201 — Gauge deposit interface: Setup: declares the gauge's deposit function in the interface.
L202 — Two-arg withdraw exists in interface: The interface exposes withdraw(_value, _claim_rewards) — the claim-enabling overload the exit path should have called instead.
L212 — Store Convex reward pool address: Setup: immutable CONVEX_REWARD_POOL holds the Convex pool address used by the other exit branch.

PoC#

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

BASH

cd 63525-inability-to-claim-rewards-from-the-curve-gauge-mixbytes-non_exp
forge test -vvv

The browser Playground replays the same synthetic opcode-for-opcode and measures the harm: Curve-gauge LP stakers receive 0 accrued CRV on exit because _unstakeLpTokens calls withdraw(poolClaim) without the _claim_rewards flag (def. Both gates are green (registry forge test PASS + Playground _verify-poc VERDICT: PASS).

Sources & further analysis#

Reproductions & code

Standalone PoC + full trace: 63525-inability-to-claim-rewards-from-the-curve-gauge-mixbytes-non_exp (evm-hack-registry mirror).
AuditVault finding: 63525-inability-to-claim-rewards-from-the-curve-gauge-mixbytes-non.
Upstream DeFiHackLabs PoC directory: src/test.

Alerts & third-party analyses

DeFiHackLabs incident explorer: search "Notional Finance: Curve-gauge LP stakers receive 0 accrued CRV on exit because _unstakeLpTokens calls withdr".
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.

Source-level debugger — step opcodes and Solidity in sync