Red Teaming LLMs via Linguistic-Aware Fuzzing

Cross-Cutting Security Analysis of LLM-Generated Code via Metamorphic Testing and Association Rule Mining

Large language models (LLMs) frequently generate code with security vulnerabilities, yet these weaknesses are rarely isolated: they often span multiple concern areas simultaneously, reflecting the cross-cutting nature of security in software. We present a framework that combines security-oriented Metamorphic Relations (MRs) with Association Rule (AR) mining to detect vulnerabilities in LLM-generated code, uncover their co-violation structure, and trace that structure back to prompt-level risk factors. We define nine MRs covering major CWE categories, including SQL injection, XSS, command injection, path traversal, hard-coded credentials, weak cryptography, and memory-safety errors, and apply them using an LLM-based judge to 3,700 code snippets generated by five open models from the LLMSecEval benchmark. The results show that 68.8% of snippets violate at least one MR, with hard-coded credentials (79.1%) and command injection (74.4%) among the most prevalent applicable failures. AR mining reveals strong cross-cutting co-violation patterns, notably that XSS and weak cryptography co-violations predict hard-coded credentials with 82.5% confidence (lift = 3.23), along with tightly coupled clusters linking authentication, credential handling, and cryptographic weakness, as well as input-handling and memory-safety failures. We then perform prompt-level risk analysis and find that database- and authentication-related prompts are strong predictors of broad cross-cutting insecurity, while 65.5% of prompts yield consistent violation outcomes across all five models. These findings show that insecure code generation is not merely a collection of independent defects, but a structured and prompt-conditioned phenomenon, motivating cluster-aware verification and prompt-level intervention for safer LLM-assisted programming.

SecMutBench: Evaluating LLM-Generated Security Tests via Mutation-Based Vulnerability Detection

Existing LLM security benchmarks evaluate code generation quality, leaving an open question: can LLMs generate tests that detect vulnerabilities? We address this with two technical contributions. First, we propose the Security Mutation Score (SMS), a metric that classifies mutant kills into semantic, functional, incidental, and crash categories using operator-aware heuristics, distinguishing genuine security awareness from coincidental detection. We further define Effective SMS (EffSMS = SMS × Secure-Pass Rate) to account for test validity. Second, we design 25 security-specific mutation operators spanning 30 CWE categories that transform secure Python code into realistic vulnerable variants, extending prior security mutation frameworks to Python and introducing 22 new operators. Evaluating eight LLMs and two static analysis baselines on 339 programs and 1,869 mutants reveals three findings: (i) traditional mutation scores overstate LLM security testing capability by 2.2× on average; (ii) the best LLM achieves only 19.7% EffSMS vs. 47.6% for expert-written tests—a 2.4× gap raw metrics obscure; and (iii) functional kills, not crashes, dominate non-semantic failures (15–36%), showing LLMs detect behavioral side-effects rather than security properties. Static analysis and mutation testing provide complementary coverage across syntactic vs. logic-flaw CWEs. Code and data are publicly available.

Hybrid Vulnerability Detection: Combining Latent Semantic Analysis with LLM-Assisted Fuzzing via Context Distillation

: As modern software systems grow in complexity, the number of vulnerabilities has grown rapidly, rendering traditional security strategies—including manual code reviews and rule-based static analyzers—increasingly resource-intensive and unable to keep pace with emerging threats. This paper presents a hybrid pipeline combining static vulnerability candidate selection using Latent Semantic Analysis with dynamic verification through Large Language Model-assisted fuzzing. The approach identifies semantically similar code patterns to known vulnerabilities without exact syntactic matches, and automates the generation of fuzzing harnesses and seed inputs to overcome coverage plateaus. We evaluate our pipeline on real-world C libraries (LibTIFF, libexpat, FreeType) with documented vulnerabilities. Results demonstrate that vulnerability candidates are ranked within the Top 3–8% of all functions, and model-generated artifacts yield a 5-fold speedup over random fuzzing. The LLM Gemini 3 Pro achieves the highest harness generation success rate at 83% (Pass@3). Our analysis reveals fundamental limitations: the mixed-vector problem dilutes vulnerability signals in multifunctional code, safety alignment mechanisms can inadvertently neutralize vulnerabilities through defensive code insertion, and static feature extraction without build context achieves only 19.93% recall. The pipeline reduces manual effort while still requiring human validation.

Large Language Model Vulnerabilities

The Language of Security: How Prompt Syntax Shapes Secure Code Generation in Open LLMs

Large Language Models (LLMs) are increasingly used for source code generation despite their outputs often exhibiting security vulnerabilities. Prior work shows that prompt engineering can mitigate such risks, yet (1) they focused on high-level prompting strategies, neglecting recent evidence that fine-grained syntactic variations can substantially alter model behavior; and (2) predominantly evaluate proprietary LLMs, limiting the applicability of their findings in industrial settings where self-hosted, open models are preferred for privacy, compliance, and deployment control. In this paper, we study how fine-grained syntactic constituents of prompts influence the security of open LLM-generated code. Using a parser-driven approach, we systematically generate syntactic variants of security-relevant code generation prompts and evaluate their impact on code security across multiple open LLMs and programming languages. Our results show that specific syntactic elements, such as constraints, guards, conditions, and concept bindings, and their position within the prompt consistently affect the likelihood of generating insecure code. These findings identify prompt syntax as a concrete security control surface and provide actionable guidance for reducing vulnerability risk in LLM-assisted development.

SOSecure: The Wisdom of the Crowd for Safer AI-Generated Code

Large Language Models (LLMs) are widely used for automated code generation. Their reliance on infrequently updated pretraining data can leave them unaware of newly discovered vulnerabilities and evolving security standards, making them prone to producing insecure code. In contrast, developer communities on Stack Overflow (SO) provide an ever-evolving repository of knowledge, where security vulnerabilities are actively discussed and addressed through collective expertise. These community-driven insights remain largely untapped by LLMs. This paper introduces SOSecure, a Retrieval- Augmented Generation (RAG) system that leverages the collective security expertise found in SO discussions to improve the security of LLM-generated code. We build a security-focused knowledge base by extracting SO answers and comments that explicitly identify vulnerabilities. Unlike common uses of RAG, SOSecure triggers after code has been generated to find discussions that identify flaws in similar code. These are used in a prompt to an LLM to consider revising the code. Evaluation across three datasets (SALLM dataset, LLMSecEval, and LMSys) shows that SOSecure achieves strong fix rates of 71.7%, 91.3%, and 96.7% respectively, compared to prompting GPT-4 without relevant discussions (49.1%, 56.5%, and 37.5%), and outperforms multiple other baselines. SOSecure operates as a language-agnostic complement to existing LLMs, without requiring retraining or fine-tuning, making it easy to deploy. Our results underscore the importance of maintaining active developer forums,