> For the complete documentation index, see [llms.txt](https://reports.immunefi.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://reports.immunefi.com/alchemix/31435-sc-high-alcx-rewards-arent-claimed-for-from-token-when-....md). # 31435 - \[SC - High] ALCX rewards arent claimed for from token when ... Submitted on May 19th 2024 at 02:47:23 UTC by @OxAlix2 for [Boost | Alchemix](https://immunefi.com/bounty/alchemix-boost/) Report ID: #31435 Report type: Smart Contract Report severity: High Target: Impacts: * Permanent freezing of unclaimed yield * Contract fails to deliver promised returns, but doesn't lose value ## Description ## Brief/Intro In `VotingEscrow::withdraw`, the protocol is claiming the ALCX rewards before burning the token, which makes sense as the token will be burnt. However, this is not done when merging 2 tokens, this puts the ALCX rewards of the "from" token at risk of being stuck forever. ## Vulnerability Details When merging 2 tokens, token\_1, and token\_2, assume that token\_1 has some unclaimed ALCX rewards, through the merge process token\_1 will be burnt. So all these unclaimed ALCX will remain stuck forever as `RewardsDistributor::claim` will revert on the following: ``` require(approvedOrOwner || isVotingEscrow, "not approved"); ``` because the token doesn't exist anymore. ## Impact Details ALCX rewards that were accumulated for the "from" token will remain unclaimable/stuck forever after the merge process. ## References ## Mitigation Add the following in `VotingEscrow::merge`: ``` IRewardsDistributor(distributor).claim(_from, false); ``` ## Proof of concept ``` function testALCXRewardsNotClaimedOnMerge() public { uint256 tokenId1 = createVeAlcx(admin, TOKEN_1, MAXTIME, false); uint256 tokenId2 = createVeAlcx(admin, TOKEN_1, MAXTIME, false); hevm.warp(minter.activePeriod() + nextEpoch); voter.distribute(); assertGt(distributor.claimable(tokenId1), 0); assertGt(distributor.claimable(tokenId2), 0); hevm.prank(admin); veALCX.merge(tokenId1, tokenId2); assertGt(distributor.claimable(tokenId1), 0); assertGt(distributor.claimable(tokenId2), 0); vm.prank(admin); vm.expectRevert(abi.encodePacked("not approved")); distributor.claim(tokenId1, false); } ``` --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation by asking a question. Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters: ``` GET https://reports.immunefi.com/alchemix/31435-sc-high-alcx-rewards-arent-claimed-for-from-token-when-....md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.