Indirect Prompt Injection in the Wild: Empirical Study Finds 15.3K Instances Across 1.2B URLs

arXiv·high signal

Researchers analyzed 1.2 billion URLs from 24.8 million hosts, identifying 15,300 validated prompt injection instances across 11,700 pages. A small set of reusable templates drives 95% of real-world injections. Evaluated effectiveness through 5,200 trials across 13 models and four page representations — the first large-scale empirical measurement of prompt injection prevalence in production web content.