[BUG]: Zero-Value Bids Bypass minBidDelta and Allow Infinite Extensions

[SIDDHANTCOOKIE]

Bug Description

Affected Component

• Contract: EnglishAuction.sol
• Function: bid(uint256 auctionId, uint256 bidAmount)

Problem Description
If an auctioneer creates an auction with a minimumBid of 0, an attacker can spam bids of 0. Because auction.highestBid is initialized to 0 and remains 0 after a zero-value bid, the condition auction.highestBid == 0 always evaluates to true. This entirely bypasses the minBidDelta requirement. The attacker can continuously bid 0 to permanently hijack the winner state and infinitely trigger the auction.deadline += auction.deadlineExtension logic without spending any funds.

Expected Behavior
Bids should be strictly greater than zero to be considered valid, preventing zero-value spam from manipulating the auction winner or extending the deadline indefinitely.

Steps to Reproduce

No response

Logs and Screenshots

No response

Environment Details

No response

Impact

Critical - Application is unusable

Code of Conduct

• I have joined the Discord server and will post updates there
• I have searched existing issues to avoid duplicates