Skip to content
Preprint

Harnessing LLMs for Document-Guided Fuzzing of Python Libraries

Aug 2026 · 0 citations · 40 references
Computer Science

TL;DR

VistaFuzz is introduced, a document-guided fuzzing technique that uses a locally served open-sourced LLM to extract parameter specifications from API documents and generate inputs that satisfy both parameter constraints and inter-parameter dependencies.

Abstract

Python libraries underpin deep learning, scientific computing, data analysis, and computer vision, making their reliability critical to downstream applications. Testing their APIs requires inputs that satisfy both per-parameter constraints and dependencies among parameters. Existing approaches either leave such constraints implicit in generated programs or rely on library-specific parsing rules. This paper introduces VistaFuzz, a document-guided fuzzing technique that uses a locally served open-sourced LLM to extract parameter specifications from API documents and generate inputs that satisfy both parameter constraints and inter-parameter dependencies. We evaluate VistaFuzz on 7,718 APIs across twelve Python libraries. Inter-parameter relationships occur in 40.1\% of tested APIs, and disabling their resolution reduces the valid generation rate on those APIs from above 95\% to 31.6\%--52.8\%. VistaFuzz reports 74 issues, of which 43 have been confirmed by developers and 29 have been fixed.

View source

Similar papers

Preprint Aug 2026

Generics-Aware Fuzz Target Generation for Rust Libraries via Structured API Analysis

Fuzzing Rust library APIs requires constructing well-typed, compilable call sequences that satisfy ownership rules, generic parameters, and trait bounds; existing tools ignore these constraints or use shallow heuristics, yielding low coverage. We present GRAFT, which extracts structured API information from Rust docume...

Yiming Chen, Kaiwen Zhang, Guanjun Liu et al. · 0 citations
#small language model Book Open access Sep 2026

Code Transformation Rule Synthesis using LLMs: Potential and Limits

A novel empirical study targeting three domain- specific languages for transformation rules, namely Comby, GritQL, and Ast-Grep, which shows great potential for LLMs to generate sound, correct, generalizable, and reusable rules.

Axel Allain, Aymeric Blot, D. Khelladi et al. · 1 citation
Open access Aug 2026

Property-based testing in Python: empirical insights

These findings provide the largest empirical characterization of PBT in Python to date, highlight developers’ difficulties in adopting the technique, and expose limitations of current tool support.

Isadora Viana Valle de Oliveira, Arthur Lisboa Corgozinho, Henrique Rocha et al. · 0 citations
Book Open access Jul 2026

From Prompts to Pareto Fronts: Using Code LMs as Semantic Genetic Operators for Compiler Bug Discovery

Differential compiler testing requires automatically generated programs that are not only diverse and bug-revealing, but also semantically well-defined and reproducible. Rule-based generators provide strong validity guarantees but offer limited control over semantic variation, while large language models (LLMs) can syn...

Lang Hong Nguyet Anh, Ho Viet Duc Luong, Vu Van An · 0 citations
Jul 2026

Portable models as a replacement for industrial heuristics in compiler optimizations

The paper investigates the possibility of predicting function-inlining decisions in compact compilers, source-to-source tools, and interpreters where the reuse of GCC or LLVM optimization infrastructure is impractical and proposes a portable inlining-prediction framework that can be emitted as ordinary C code without a...

F. Nikolai, Vinarsky Alexander · 0 citations
Preprint Aug 2026

From Documentation to Zero-day Vulnerabilities: LLM-Driven Fuzzing of JavaScript Engines in PDF Readers

Existing fuzzers for PDF readers rely on simple test cases that involve only individual API calls, leading to limited coverage and potentially missing vulnerabilities that require sequences of API calls. To address these limitations, we propose PDFuzzer, a novel PDF engine fuzzer that automatically generates complex an...

Suyue Guo, Stijn Pletinckx, Tianle Yu et al. · 0 citations

We use cookies to run the site and, with your consent, for analytics and to show ads. See our Cookie Policy.