Your agent shipped the upload endpoint. The feature works, the demo works, the pull request is tidy. Somewhere inside it, the filename a user uploads is also a path, and nobody tested that. A benchmark published on October 10, 2026 puts a number on how often that happens. The Last Secure Code Benchmark (LSCBench, arXiv:2610.14766) took 150 real vulnerabilities, expanded them into 450 tasks across seven languages, and handed them to six frontier coding agents. The prompts asked only for functi...