Session 13A: JavaScript Security  Authors, Creators & Presenters: Liam Wachter (EPFL), Julian Gremminger (EPFL), Christian Wressnegger (Karlsruhe Institute of Technology (KIT)), Mathias Payer (EPFL), Flavio Toffalini (EPFL) PAPER DUMPLING: Fine-Grained Differential JavaScript Engine Fuzzing Web browsers are ubiquitous and execute untrusted JavaScript (JS) code. JS engines optimize frequently executed code through just-in-time (JIT) compilation. Subtly conflicting assumptions between optimizations frequently result in JS engine vulnerabilities. Attackers can take advantage of such diverging assumptions and use the flexibility of JS to craft exploits that produce a miscalculation, remove bounds checks in JIT compiled code, and ultimately gain arbitrary code execution. Classical fuzzing approaches for JS engines only detect bugs if the engine crashes or a runtime assertion fails. Differential fuzzing can compare interpreted code against optimized JIT compiled code to detect differences in execution. Recent approaches probe the execution states of JS programs through ad-hoc JS functions that read the value of variables at runtime. However, these approaches have limited capabilities to detect diverging executions and inhibit optimizations during JIT compilation, thus leaving JS engines under-tested. We propose DUMPLING, a differential fuzzer that compares the full state of optimized and unoptimized execution for arbitrary JS programs. Instead of instrumenting the JS input, DUMPLING instruments the JS engine itself, enabling deep and precise introspection. These extracted fine-grained execution states, coined as (frame) dumps, are extracted at a high frequency even in the middle of JIT compiled functions. DUMPLING finds eight new bugs in the thoroughly tested V8 engine, where previous differential fuzzing approaches struggled to discover new bugs. We receive $11,000 from Google's Vulnerability Rewards Program for reporting the vulnerabilities found by DUMPLING.  ABOUT NDSS The Network and Distributed System Security Symposium (NDSS) fosters information exchange among researchers and practitioners of network and distributed system security. The target audience includes those interested in practical aspects of network and distributed system security, with a focus on actual system design and implementation. A major goal is to encourage and enable the Internet community to apply, deploy, and advance the state of available security technologies.  Our thanks to the Network and Distributed System Security (NDSS) Symposium for publishing their Creators, Authors and Presenter’s superb NDSS Symposium 2025 Conference content on the Organizations' YouTube Channel.  Permalink

Security Boulevard is a leading cybersecurity news and information portal, offering articles, analysis, and insights on cybersecurity threats, vulnerabilities, and best practices. From the latest trends in cyber threats to expert commentary on security technologies and compliance frameworks, Security Boulevard provides resources for security professionals, IT leaders, and business executives seeking to protect their organizations from cyber attacks and data breaches.

Security Boulevard

DUMPLING is a differential fuzzer presented at NDSS 2025 that detects vulnerabilities in JavaScript engines by comparing full execution states of optimized and unoptimized code. Unlike prior approaches that instrument JS input with ad-hoc functions, DUMPLING instruments the JS engine itself to extract fine-grained frame dumps at high frequency, even mid-JIT-compiled functions. This enables deeper introspection without inhibiting JIT optimizations. Applied to V8, DUMPLING discovered eight new bugs and earned $11,000 from Google's Vulnerability Rewards Program.

NDSS 2025 -DUMPLING: Fine-Grained Differential JavaScript Engine Fuzzing