Why Token Approvals, MEV Risk, and Multi-Chain Security Should Keep You Up at Night — and How to Sleep Better

Whoa!

For years I clicked “Approve” without thinking. It felt normal. Really? Yep. My instinct said somethin’ was off the first time a DEX routed my swap through three chains and charged what looked like a stealth toll, but I didn’t stop to check approvals then. Initially I thought approvals were just a UX annoyance, but after a few close calls I realized they’re a systemic risk that links everyday DeFi behavior to sophisticated MEV extraction and cross-chain attack surfaces.

Here’s the thing.

Token approvals give smart contracts permission to move tokens on your behalf, and that power, if mismanaged, is catastrophic. On one hand approvals enable seamless UX and composability; on the other hand they create a persistent attack vector, because a single malicious contract or a compromised router can drain an approved balance. That’s a big contradiction in DeFi design — convenience versus persistent authority — and actually, wait—let me rephrase that so it’s clearer: approvals are both the plumbing that makes DeFi usable and the smoke alarm that only sometimes works when things catch fire.

Seriously?

Yes. Approvals are often unlimited and forever. Developers do this to avoid repeated gas costs, and users accept it because signing once is less friction. But forever approvals mean an exploit of a single contract can empty wallets long after the initial interaction. On the macro level, this combines with MEV actors who scan mempools and sandwich trades, and with cross-chain bridges that expand the blast radius, creating complex adversarial opportunities that are easy to miss until it’s too late.

Hmm…

At a personal level I learned this the hard way. Once, late-night, I approved an aggregator without vetting its allowance scheme. Next morning there was an unauthorized transfer attempt via a second-party contract that had been allowed to route funds. I caught it in time because I was monitoring approvals. It was a wake-up call — and it changed how I evaluate wallets and approvals. I’m biased, sure, but that experience taught me to treat approvals like recurring subscriptions: check them each month.

Wow!

So what do savvy users do differently? They practice least-privilege approvals, prefer per-use allowances, and use tools that let them revoke permissions quickly. They also treat approval management as a first-class security habit, similar to rotating keys or using hardware where possible. On top of that, they look for wallet features that protect against MEV and offer multi-chain insights so no approval slips through unnoticed just because it was on an unfamiliar chain.

How wallets can help — and what to look for in a multi-chain solution like rabby wallet

Okay, so check this out—wallets are the frontline.

They can surface all active approvals, across chains, in one view. They can offer one-click revokes and show you who currently has permission to move which token amounts, and they can warn you when you hit “Approve” for infinite allowances. But not all wallets are created equal — some only show ERC-20 approvals on Ethereum mainnet and ignore BSC, Polygon, or Arbitrum, which creates blind spots. I’d rather use a wallet that tells me “hey, you’ve got an open approval to a contract on Optimism,” because once you lose visibility across chains, your security posture suffers silently.

My instinct said: multi-chain visibility is non-negotiable.

On top of that, wallets can mitigate MEV in client-side ways: they can suggest alternative RPC endpoints that reduce mempool exposure, build in transaction bundling or relay support to send transactions directly to miners/validators, and integrate with protected RPCs that offer front-running shields. These are not perfect solutions, but they lower the odds that your signed transaction becomes a target of sandwich attacks or other MEV bots that profit off positional timing.

Here’s what bugs me about most solutions.

They make security optional and buried. The “revoke” action is often three menus deep. The UX prioritizes speed over control. That tradeoff makes sense for onboarding novices, though actually it also creates systemic risk for everyone when bad actors learn the common patterns. A better wallet flips that default: security first but smooth, with clear friction only where it matters — like a brief confirmation when making a new unlimited approval.

Whoa!

Let me walk through a practical approval-management checklist I use, and I recommend you adapt it. Step one: only give per-transaction allowances where possible. Step two: after any DEX or aggregator trade, immediately review the spender’s allowance for that token. Step three: revoke or set a zero allowance if you don’t plan to use the contract again. Step four: maintain a monthly audit of approvals across chains, because exploits and compromises don’t respect time zones. These steps take minutes and they matter.

Initially I thought gas cost was the main blocker to per-use approvals,

but then I realized that modern wallets can batch revokes or offer meta-transactions to reduce cost friction, so the excuse is weaker than it used to be. Also, new UX patterns like “one-tap autopilot where the wallet sets a spend limit” are emerging — they keep convenience while limiting persistent authority. This evolution matters, because as DeFi goes multi-chain, the number of contracts you interact with goes up exponentially, and so does the probability of a leftover dangerous approval.

Really?

Yes — and MEV complicates the story further. MEV is no longer just about extracting value from single-chain mempools. Cross-chain MEV strategies and bridge routing can create chains of swaps where approvals and routing decisions feed each other, enabling adversarial participants to craft multi-transaction combos that profit from poorly managed allowances. On one hand, MEV research has driven infrastructure improvements; though actually, on the other hand, it has also taught attackers new techniques. It’s complicated.

I’m not 100% sure of every vector,

but here’s a reasonable threat model: an attacker finds a vulnerable aggregator contract, uses an approved allowance to move tokens to a bridge contract, then routes them through a sequence of chains to obfuscate provenance. Detection happens slowly, and by the time alerts trigger, funds are fragmented across chains. Recovery is tedious or impossible, especially given cross-chain custody issues. That worst-case scenario isn’t theoretical — it’s a plausible chain of failures.

Hmm…

So where do we put our trust? In wallets that combine permission management, MEV-aware transaction routing, and clear multi-chain UX. Tools that let you watch approvals, simulate the effects of revoking, and send protected transactions are worth their weight in saved funds. Hardware keys remain essential for private-key safety, but they don’t solve approval creep — only better approval controls will do that. And note: even good hardware wallets need front-end partners that behave sensibly.

Okay, real talk.

I’m biased toward wallets that give power back to users without making them feel like security engineers. I like when a wallet flags risky approvals and explains, in plain English, what happens if you revoke versus keep them. I’m also a fan of features that make protected transactions the default path when interacting with unknown contracts, and again, I’m not 100% sure there’s a single correct answer for all users — risk tolerance matters — but default protection reduces accidental losses across the board.