A Cairo audit is a security review of Starknet contracts written in Cairo, focused on field-element arithmetic that does not behave like integer arithmetic, native account abstraction changing what caller identity means, L1 to L2 message handling, and the contract class and upgrade model.
Cairo's primitive type is a field element, not a machine integer. Arithmetic wraps around the prime field, so a subtraction that "cannot go negative" produces an enormous positive value instead, and a range check you did not write is a range check that does not exist. This single difference invalidates a great deal of intuition carried over from Solidity, and it is the source of a large share of the findings we report on Cairo code.
The second source is account abstraction. On Starknet every account is a contract, so signature validation, multicall behaviour and the meaning of the caller address are all contract-defined rather than protocol-guaranteed. We review the account contracts, the entry point validation split, and every place your logic assumes the caller is a simple key-holder.
We fix a commit hash, agree the in-scope contracts and read your architecture docs, then build a threat model: who the actors are, what the trust boundaries are, and which invariants must never break. Nothing is reviewed against assumptions we have not written down.
Line-by-line review by at least two auditors working independently, focused on authorisation, accounting, upgrade paths, external integrations and the gap between what the code does and what the documentation claims it does. Most critical findings come from this phase, not from tooling.
Static analysers appropriate to the language, plus property-based fuzzing and invariant testing to push the system into states no unit test covers. Tooling is used to widen coverage, never to replace the manual pass.
Candidate findings are proven on a forked network with a working proof of concept. We report what an attacker can actually do and what it costs them, not a theoretical severity label.
Every finding gets a severity rating, reproduction steps, the affected code, the impact in concrete terms and a specific remediation. You get a draft for discussion before anything is finalised.
We re-test every remediation against the original proof of concept and check that the fix has not opened a new path. The final report is yours to publish.
Because felts are field elements, not integers. Underflow does not revert — it produces a huge positive number. Any comparison or balance check written with Solidity intuition can be wrong in a way that compiles and passes happy-path tests.
Yes, and modern Cairo with its component model is the common case. We also review older Cairo 0 code where a migration is in progress, which has its own bug classes at the boundary.
Yes. On Starknet the account contract is a security boundary in a way it never is on Ethereum, and a weak validate implementation compromises everything the account can reach.
Yes — the Solidity bridge or messaging contract on L1 is part of the same system, and most messaging findings live at the seam between the two sides.
A repository or contract address, a commit hash to freeze the scope, whatever architecture or spec documentation exists, and a point of contact who can answer design questions. If documentation is thin we will write our understanding of the system back to you and ask you to confirm it — that step alone catches design-level bugs.
A single token contract is 24–48 hours. A typical dApp or mid-sized protocol runs one to two weeks. Large DeFi systems, L2s, bridges and ZK circuits are scoped per project after we have seen the code. We will give you a fixed timeline with the quote, not an estimate that moves.
Yes. Fix review is part of the engagement, not an upsell. We re-run the original proof of concept against your patched code and confirm the fix has not introduced a new path.
Send the repository and a commit hash through the contact form, message @bugtester25 on Telegram, or book a 30-minute scoping call. 200+ protocols audited · $4B+ secured · 0 hacks post-audit. Prefer email? info@safeedges.in.