Venus Prime — stale staking timestamp permits a free revocable Prime claim

Source & credit. Reproduction of a public audit finding curated by AuditVault — the original finding: 28832-h-01-primesol-user-can-claim-prime-token-without-having-any. Standalone Foundry PoC and full write-up: 28832-h-01-primesol-user-can-claim-prime-token-without-having-any_exp in the evm-hack-registry mirror.

Vulnerability classes: vuln/logic/incorrect-state-transition · vuln/logic/state-update · vuln/reward-theft

Reproduction: self-contained Foundry PoC with no fork, RPC, or cheatcodes. Full trace: output.txt. Driver: test/28832-h-01-primesol-user-can-claim-prime-token-without-having-any_exp.sol.

AuditVault taxonomy: lang/solidity · sector/governance · sector/staking · platform/code4rena · has/github · has/poc · severity/high · genome: wrong-condition · reward-theft · timestamp-dependence

Key info#

TL;DR#

stakedAt determines whether an account has waited long enough to claim a revocable Prime token. The irrevocable issue branch mints the token but does not clear that timestamp. A user can enter that branch, withdraw all XVS, burn the irrevocable token, wait out the original clock, and then claim a revocable token while holding no stake.

The local PoC stakes 10,000 units, issues the irrevocable token, withdraws the entire stake, burns it, advances the local clock, and successfully claims the revocable token. It asserts both zero staked balance and the unauthorized claim.

The vulnerable code#

if (irrevocable) {
    _mint(true, users[i]); // @> VULN: stakedAt[users[i]] is not deleted
}

The revocable paths clear this eligibility timestamp. This exceptional irrevocable path leaves it live even though the user can later own no qualifying stake.

Root cause#

Eligibility state is coupled to the stake lifecycle but is not reset on every token state transition that invalidates the prior eligibility context. The stale timestamp is subsequently trusted by claim as though the user were still staked.

Preconditions#

• A user can receive an irrevocable Prime token before the staking duration ends.
• The user can withdraw its XVS and burn or otherwise dispose of that token.
• The old stakedAt value passes the configured duration when claiming.

Attack walkthrough#

1. The attacker stakes, establishing stakedAt.
2. The protocol issues an irrevocable Prime token through the vulnerable branch.
3. The attacker withdraws all stake and burns the irrevocable token.
4. After the original delay, claim accepts the stale timestamp and mints a revocable token without any XVS collateral.

Diagrams#

Remediation#

Clear eligibility state when issuing an irrevocable token, matching the other issuance and claim branches:

delete stakedAt[users[i]];
_mint(true, users[i]);

Also test every transition that removes stake or changes token type before relying on a historic timestamp for a new privilege.

How to reproduce#

cd /workspaces/RustroverProjects/audits/evm-hack-registry/28832-h-01-primesol-user-can-claim-prime-token-without-having-any_exp
forge test -vvv

Sources#

• AuditVault finding #28832
• Code4rena Venus report

Reference: Code4rena Venus finding H-01, curated by AuditVault.

Sources & further analysis#

Reproductions & code

• Standalone PoC + full trace: 28832-h-01-primesol-user-can-claim-prime-token-without-having-any_exp (evm-hack-registry mirror).
• AuditVault finding: 28832-h-01-primesol-user-can-claim-prime-token-without-having-any.

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.