ACP-267: Primary Network validator uptime requirement increases from 80% to 90%.Read the proposal

Playing Defense: Spam Prevention on Avalanche C-Chain

How we're protecting the C-Chain from state bloat and validators from being flooded with expensive spam transactions.

Back

The Anomaly

We watch a lot of dashboards, and few months back, we noticed something odd: when gas prices fell to near-zero levels, we'd see sustained floods of transactions that looked like... nothing useful.

Not an attack. Not MEV. Just relentless, trivial transactions exploiting cheap gas to pile up state changes. Let's call it what it is: spam.

Why Spam Matters

You might think: "They're paying gas fees. Protocol's working as intended."

Technically true. But spam compounds over time:

State Bloat: Every transaction grows the state trie. Validators and RPC nodes need more storage, more memory, more everything. "Just a few extra gigabytes" becomes "why is my node falling behind?"

Validator Performance: Nodes on-spec hardware struggle during spam bursts. Processing slows. Uptime dips.

Economic Pressure: Validators with poor uptime risk losing rewards. Spam penalizes honest validators just trying to keep up.

Rising Costs: State growth raises the barrier for new validators. That 500GB SSD? Now you need 2TB.

Why Does Spam Happen?

When gas drops to rock-bottom levels, flooding the network becomes economically trivial. Some spam is just strange: contracts that do nothing, transactions that accomplish nothing. But they're cheap, so why not?

The Solution

We implemented a countermeasure that activates during abnormally low gas periods:

We issue transactions that intentionally fail.

Here's how:

Detect Low-Fee Conditions

When gas prices drop below thresholds, our monitoring triggers the anti-spam mechanism.

Issue Failing Transactions

We send transactions calling the INVALID opcode. These:

  • Consume gas (raising base fee)
  • Execute no state changes (fail immediately)
  • Displace spam by competing for block space

If spammers flood blocks at 1 Gwei, we use that gas ourselves. Base fee rises, spam gets expensive, spammers back off.

Pay for Gas

No admin privilege. We pay for every transaction. This is economic action, not protocol bypass.

The Metrics Question

"Are you gaming metrics?"

Nope. Here's exactly how our approach affects key metrics:

Gas Used: We're displacing spam, not inflating usage. The network consumes that gas either way. Net effect: ~0% change

TPS: Our transactions fail immediately and are issued sparingly. TPS looks nearly identical. Net effect: ~0% change

Active Accounts: We use one account. Spam creates thousands. Net effect: +1 account

Application Metrics: No contract interactions. No DeFi, USDC, or native transfers. If you're tracking real usage, we're invisible. Net effect: 0% change

Results

Since implementing:

  • State growth rate during spam periods decreased
  • Validator uptime variance stabilized
  • Gas price floor stays healthy (spam becomes uneconomical faster)

The network doesn't look busier. It's just healthier under the hood.

What's Next?

This is temporary while we explore protocol-level improvements:

  • Dynamic minimum gas pricing
  • State rent mechanisms
  • Enhanced fee market designs
  • Independent OPCODE gas pricing
  • Validator spec optimizations

The goal: build a protocol where spam isn't worth attempting.

Wrapping Up

Running a blockchain means making trade-offs. We chose economic intervention that's transparent, metrics-neutral, and immediately effective. We're paying for gas to keep the network healthy while longer-term improvements ship.

The C-Chain belongs to its community: developers, validators, users, and builders. When we make moves like this, we believe in showing our work.

Questions? Find us in the Avalanche Discord or open an issue on GitHub.


Building in public. Always.

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On

Fri Feb 20 2026

Topics

C-ChainNetwork SecurityState ManagementGas Economics