Why SAST Misses the Hardest Vulnerabilities

Static application security testing (SAST) has been a go-to for scaling code review, but it has a blind spot that Codex Security is tackling head-on. The team behind it realized that the biggest security issues aren’t just about tracking data from input to output—like finding where user input flows into a sensitive function without sanitization. That’s the part SAST handles okay. The real problem is whether the security checks in your code actually work as intended. For example, a static analyzer can see a function like sanitize_html() was called, but it can’t tell if that specific sanitizer is good enough for your particular template engine or encoding context. So you might think you’re safe because a check runs, but a subtle mismatch between the sanitizer and the rendering context can leave a gaping hole. Codex Security flips the script by starting with the repo’s architecture and trust boundaries, then validating findings before bugging humans. Why it matters: This shift from ‘did code run a check?’ to ‘does the check actually protect the system?’ could redefine how we think about automated security analysis, especially as AI-generated code introduces even more nuanced vulnerabilities.