Skip to content
← Intel Brief
Onchain · Audit

Reentrancy in 2026: the bugs that refuse to die

A modern field guide to reentrancy variants and the patterns that still slip past automated tooling.

Abstract smart contract call loops representing a reentrancy vulnerability
AN3 Security · · 9 min read

Reentrancy didn't die with The DAO. It evolved — into read-only reentrancy, cross-function reentrancy, and ERC-777 callback chains that static analyzers still miss.

The patterns we still find

  • Cross-function reentrancy — state updated in function A, exploited via callback into function B
  • Read-only reentrancy — oracle manipulation without moving funds
  • ERC-777 hooks — tokensReceived callbacks mid-transfer

Detection beyond scanners

Automated tools catch the textbook call → transfer ordering bug. They miss the variants above unless you model the full call graph and state transitions by hand.

AN3 Intel Brief · Smart contract audits by operators who ship exploits.