Best Smart Contract Language for Security: What Audits Show

By the Guardian team Updated November 2026 7 min read

Quick answer. No language is safest: each removes some bug classes and adds others. Logic errors, which none prevents, are about half of Critical and High findings in Guardian's 320 public reports: 52.9% in Solidity, 7 of 14 in Rust.

Watch: Best Smart Contract Language for Security: What Audits Show 1:48

Video transcript

Which smart contract language is the most secure? None. Each one removes some bug classes and adds others, and logic errors get through in every language.

Languages remove mechanical bugs, like silent overflow or assets copied and lost. But none of them knows what your protocol is supposed to do.

Each language removes some bugs and leaves others. Solidity reverts on overflow since version 0.8.0. Vyper leaves out features that make code misleading. Move stops assets being copied or lost, and DAML enforces party authority.

Across Guardian's 320 public reports, logic errors lead. They are 52.9 percent of Solidity's Critical and High findings, and 7 of Rust's 14. Reentrancy appears in only 9 of Solidity's 1,141.

This is not a ranking. The sample size is uneven, 289 Solidity reports against 18 in Rust. Findings are concentrated, and the mix of clients, scope and code maturity differs by ecosystem.

Rust shows the same pattern. Solana blocks indirect reentrancy, yet all five Criticals in Guardian's public Degen Safe report were missing account or initialization checks.

Choosing a stack? Start from the chain, which usually fixes the language. Use the safety features you get, fuzz your rules as invariants, pin the compiler, and budget expert review for logic.

A Guardian smart contract audit runs three passes on any stack: design review, an invariant suite for solvency and accounting, and manual review by senior researchers.

Read the full breakdown by language, or get an audit quote from Guardian at guardian.security.

Teams choosing a stack often ask which smart contract language is the most secure. The useful answer is narrower than a ranking.

A language can make some bugs impossible. It cannot make a protocol's rules correct.

We counted Critical and High findings by language across Guardian's 320 public audit reports. Then we checked each language's own docs for what it removes and what it adds.

What a Language Can Prevent

Languages remove mechanical bug classes: math that wraps silently, calls that re-enter, assets copied or lost, actions taken without authority.

They also add classes of their own, through the execution model, the framework or the compiler.

Language	Removes or reduces	Still on you
Solidity	Silent overflow, since 0.8.0	Reentrancy, `tx.origin` auth, unbounded loops, `unchecked` math
Vyper	Hidden logic (no modifiers, inheritance, assembly, overloading); overflow; unbounded loops	Compiler bugs; reentrancy where no lock is set
Rust on Solana	Indirect reentrancy; owner checks with Anchor types	Account relationships; overflow wraps in release builds by default
Move	Copying or dropping assets; overflow on + and *	Signer and object checks, generics, left shifts, some reentrancy
Cairo	Overflow in integer types	`felt252` math wraps modulo a prime
DAML	Creates and exercises without the right parties' authority	Business rules and choice design

None of them knows what your protocol is supposed to do. That gap holds the largest share of serious findings: see business logic vulnerabilities.

Critical and High Findings by Language

Guardian's portfolio holds 320 public reports with 343 Critical and 845 High findings. Reports carry language tags.

Language	Reports	Critical	High	Per report	Reports with any	Critical or High share
Solidity	289	335	806	3.95	60%	13.1%
Rust	18	7	7	0.78	22%	4.2%
DAML	2	0	1	0.50	50%	1.0%
Move	1	0	0	0.00	0%	0.0%

How we counted

Data. All 320 public reports on November 5, 2026, by each report's language tags. Soroban counts as Rust.
Findings. Each goes to the language of the file it cites. Findings in offchain code are left out, as are 7 Critical or High findings in mixed reports that cite no file.
Per report. Critical plus High findings, divided by reports in that language. "Reports with any" have at least one.
Excluded. 11 reports with no language tag, and 4 tagged only with offchain languages. Severity is as published.

Why this is not a ranking

Sample size. 289 Solidity reports, against 18 Rust, 2 DAML and 1 Move. Only Solidity has enough to read as a rate. There are no Vyper or Cairo reports.
Concentration. Rust's 7 Criticals come from 3 reports, 5 of them from one. Solidity's 335 come from 87 reports.
Mix. Clients, scope size and code maturity differ by ecosystem. Language is one factor of many.

Solidity and Rust share a pattern: logic errors lead. They are 52.9% of Solidity's 1,141 Critical and High findings, and 7 of Rust's 14.

The mechanical classes are rare. Reentrancy appears in 9 of Solidity's 1,141 Critical and High findings, by title or category.

Solidity and Vyper

Both compile to the EVM, so they share its hazards. An external call hands over control, and the block gas limit caps loops.

Solidity

Since 0.8.0, arithmetic reverts on overflow and underflow. An unchecked block restores the old wrapping behavior.

Solidity's security docs still list reentrancy, tx.origin authorization, unbounded loops and failed Ether sends as pitfalls.

Checked math changes the failure, not always the impact. 21 Solidity Critical or High findings name an overflow or underflow; at least 12 of them are a revert, lockup or DoS.

A sum that reverts can freeze a withdrawal or a settlement. Compilers have bugs too: see Solidity compiler bugs.

Vyper

Vyper leaves out modifiers, class inheritance, inline assembly and overloading, which its docs say make code misleading or hard to follow.

It also drops recursion and infinite loops, so every call has an upper bound on gas.

It checks bounds and overflow on array access and arithmetic.

Reentrancy protection is opt-in. @nonreentrant takes a global lock, and since 0.4.2, #pragma nonreentrancy on locks external functions by default.

The compiler is part of the attack surface. A Critical Vyper advisory says versions 0.2.15 to before 0.3.1 allocated named reentrancy locks incorrectly, allowing cross-function reentrancy.

Rust-Based Stacks

Of Guardian's 18 Rust reports, 4 are on Stellar's Soroban. Most of the rest are Solana programs.

In Rust, overflow depends on the build. The Rust Book says debug builds panic on overflow, while release builds wrap.

It calls relying on that wrapping an error, and offers checked_* methods instead.

Solana and Anchor

Anchor's Account type checks an account's owner when it deserializes it. Signer checks a signature, and UncheckedAccount checks nothing.

Ownership is not the whole story. Anchor does not know that a stake record must belong to this user, or a vault to this pool.

The runtime removes one EVM hazard. Solana rejects indirect reentrancy (A calls B calls A), though direct self-recursion is allowed.

The five Criticals in Guardian's public Degen Safe report were all missing account or initialization checks:

C-01, C-04 and C-05: init_if_needed let anyone re-run setup and overwrite the owner or authority.
C-02: withdrawals accepted any user's stake account.
C-03: the vault's PDA seeds left out the pool, so pools with the same reward token shared one vault.

Orderly's C-01 was the same kind: a SOL deposit accepted another allowed token's hash. All six were resolved.

For the review checklist, see our Solana audit guide.

Move, Cairo and DAML

Move

Move builds asset safety into its types. A type without copy cannot be duplicated, and one without drop cannot be lost.

Aptos's security guidelines say addition and multiplication abort on overflow, but left shift does not.

They also say Move historically prevented reentrancy, and that function values now make some forms possible.

Access control stays manual. The guidelines say to verify that the signer owns an object, and to check generic types.

The portfolio holds 1 Move report, Mysten Labs' suiUSDe review, with no Critical or High findings. That is too few to compare.

Cairo

Cairo's base type, felt252, is a field element. Results outside its range wrap modulo a large prime.

Its fixed-size integer types check overflow and underflow, and an underflow panics. The Cairo Book recommends them over felt252.

DAML

DAML puts authorization in the ledger. Creating a contract needs its signatories' authority, and exercising a choice needs its controllers'.

The docs leave business validity to you: their example Iou, with no ensure clause, accepts negative amounts.

Guardian's 2 public DAML reports hold 1 High finding, in LayerZero's Canton DAML review (H-01).

An inbound amount was accepted before the code checked it would still fit a 64-bit integer after decimal scaling. It was resolved; see our DAML audit guide.

How to Choose

Start from the chain. It usually fixes the language: Solidity or Vyper on the EVM, Rust on Solana, Move on Sui or Aptos, Cairo on Starknet, DAML on Canton.
Use the safety features you get: Vyper's nonreentrancy pragma, Anchor's typed accounts, Rust's checked_* math, Cairo's integer types.
Write the protocol's rules as invariants and fuzz them. No language checks your accounting.
Pin the compiler version and track its advisories.
Run scanners on every change for the mechanical classes. See what free scanners miss.
Budget expert review for logic: about half of Critical and High findings in Solidity and Rust alike.

How Guardian Audits Every Stack

Guardian's public portfolio covers Solidity, Rust on Solana and Stellar, Move and DAML. Every count in this post can be checked against it.

A Guardian smart contract audit runs three passes: design review, an invariant suite and manual review by senior researchers.

The invariant suite targets what languages cannot: solvency, accounting, rounding and edge states.

Frequently Asked Questions

Which smart contract language is the most secure?

None is safest in every respect. Vyper, Move and DAML remove specific bug classes by design. Logic errors, about half of Guardian's Critical and High findings in Solidity and Rust, remain possible in every language.

Is Rust safer than Solidity for smart contracts?

Not by itself. Solana's runtime blocks indirect reentrancy, but programs must validate the accounts they receive, and Rust release builds wrap on overflow by default. Guardian's 18 public Rust reports are too few to rank against its 289 Solidity reports.

Is Vyper safer than Solidity?

Vyper removes features that can hide behavior, such as modifiers, inheritance and inline assembly, and checks bounds and overflow. It runs on the same EVM, and a compiler bug in versions 0.2.15 to before 0.3.1 broke named reentrancy locks.

Can a safer language replace a smart contract audit?

No. In Guardian's public reports, logic errors are 52.9% of Solidity's Critical and High findings, and 7 of Rust's 14. A language cannot know your protocol's rules; invariants and expert review can.

Sources

Audit your stack, whatever the language

Guardian reviews Solidity, Rust, Move and DAML code against the rules your protocol must keep.

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