BhargavaShastry

Differential fuzzing and hard-fork readiness testing across Ethereum execution clients — finding consensus divergences before they reach mainnet.

• Coverage-guided differential fuzzing of state-test execution across geth, Besu, Nethermind, Erigon, and revm, built on goevmlab
• Hard-fork readiness testing for upcoming upgrades: gas repricing, block-level access lists, and new EIP semantics validated against the executable specs
• Upstream fixes merged in Erigon, Nethermind, revm, and ethereum/execution-specs
• Earlier: EIP-7702 differential fuzzers across geth, Nethermind, and Besu; PrecompileFuzzer for the Prague hard fork; EthFuzzNet network-resilience testing

Technical evaluator for the Ethereum Foundation bug bounty program: reproducing, assessing, and routing reported vulnerabilities across execution- and consensus-layer clients.

• Evaluate submissions for consensus, finality, and denial-of-service impact to assign severity
• Reproduce reported issues and confirm cross-client blast radius with differential test harnesses
• Built internal tooling that manages the submission-to-triage workflow end to end

Differential testing of post-quantum standards: cross-checking independent ML-KEM (FIPS 203) and ML-DSA (FIPS 204) implementations against each other.

• Built a coverage-guided differential fuzzer co-linking mlkem-native, BoringSSL, and libcrux
• Functional-equivalence and constant-time checks across implementations
• Published a four-part blog series on the approach and results

Agentic systems that put LLMs to work on Ethereum client security: deterministic orchestration, auditable logs, and human review at the decision points.

• Agent frameworks that decompose vulnerability research into context building, harness generation, PoC validation, and triage
• Autonomous audit pipelines run against Ethereum client codebases in sandboxed environments
• LLM-assisted severity assessment integrated into the bug bounty triage workflow

Core contributor to the Solidity compiler's testing infrastructure, with 300+ commits focused on fuzzing and correctness testing.

• 303 commits to the Solidity compiler, primarily in fuzzing and testing
• Built ABI encoder v2 differential fuzzer
• Discovered and reported numerous compiler correctness bugs through structure-aware fuzzing

Security testing of peer-to-peer networking stacks used in Ethereum consensus and execution clients.

• Security testing of Ethereum wire protocols (eth/6x, snap/1), including upstream sync-protocol fixes merged in Nethermind
• Fuzzed libp2p (Rust implementation) for protocol-level vulnerabilities
• Built mplex-dos stress testing tool for libp2p multiplexing
• Contributed yamux stream multiplexer security patches
• Security research on Prysm (Ethereum consensus client)

Tools and frameworks for automated vulnerability discovery, contributed to Google's OSS-Fuzz and built standalone fuzzing frameworks.

• Built orthrus, a fuzzing framework for managing parallel fuzz campaigns (216 commits)
• 69 commits to Google's OSS-Fuzz continuous fuzzing platform
• Developed custom protocol-buffer based mutation strategies for structure-aware fuzzing

Fuzzing open-source networking and language runtime software to find and fix memory safety and logic bugs.

• Fuzzed Open vSwitch (16 commits) — found packet parsing vulnerabilities
• Contributed to OVN (16 commits) — virtual network security testing
• Built mruby proto fuzzer using structure-aware fuzzing techniques
• Discovered and reported Boost Filesystem crash bugs

Testing and compliance infrastructure for Ethereum's account abstraction ecosystem.

• Built bundler test executor for ERC-4337 compliance testing
• Contributed to Holesky funding vault smart contract infrastructure