#59031 [SC-Low] periodattimestamp returns incorrect period numbers for non current timestamps

Submitted on Nov 7th 2025 at 21:37:11 UTC by @Falendar for Audit Comp | Firelight

• Report ID: #59031

• Report Type: Smart Contract

• Report severity: Low

• Target: https://github.com/firelight-protocol/firelight-core/blob/main/contracts/FirelightVault.sol

• Impacts:

  • Contract fails to deliver promised returns, but doesn't lose value

Description

Brief/Intro

The periodAtTimestamp function doesn't return the correct period for the provided timestamp.

Vulnerability Details

The vulnerability exists in the interaction between two functions:

function periodAtTimestamp(uint48 timestamp) public view returns (uint256) {
    PeriodConfiguration memory periodConfiguration = periodConfigurationAtTimestamp(timestamp);
    return periodConfiguration.startingPeriod + _sinceEpoch(periodConfiguration.epoch) / periodConfiguration.duration;
}

function _sinceEpoch(uint48 epoch) private view returns (uint48) {
    return Time.timestamp() - epoch;
}

The bug occurs because:

1. periodAtTimestamp(timestamp) accepts a timestamp parameter indicating which point in time to query

2. It correctly uses this parameter to fetch the appropriate periodConfiguration via periodConfigurationAtTimestamp(timestamp)

3. However, when calculating the period number, it calls _sinceEpoch(periodConfiguration.epoch) which ignores the input parameter and uses Time.timestamp() (current block time) instead

4. This means the elapsed time calculation uses the wrong reference point: current time instead of the queried timestamp

Impact Details

Any external protocol, contract, user or future implementations that calls periodAtTimestamp for historical analysis will receive incorrect data.

References

https://github.com/firelight-protocol/firelight-core/blob/db36312f1fb24efc88c3fde15a760defbc3e6370/contracts/FirelightVault.sol#L246-L250

Proof of Concept

Proof of Concept

Example

periodConfigurations[0] = {epoch: 1000, duration: 100, startingPeriod: 0}

Period timeline:

Period 0: 1000-1100

Period 1: 1100-1200

Period 2: 1200-1300 (this is the period that needs to be retrieved)

...

Period 10: 2000-2100

Current blockchain timestamp: Time.timestamp() = 2000

Retrieving period at timestamp 1250: vault.periodAtTimestamp(1250);

elapsed = Time.timestamp() - 1000 = 2000 - 1000 = 1000

periodsElapsed = 1000 / 100 = 10

periodNumber = 0 + 10 = 10 (current value, WRONG)

Result: Returns Period 10 instead of Period 2 (always returns current period)