Code breaks. Attackers wait. One missed flaw, and they are in before you can patch. That is the zero day risk that hides inside your software. Cheap fixes after release do not solve it. You have to catch it before the build ships.
IAST — Interactive Application Security Testing — does that while your app runs. It watches traffic, inspects code paths, and flags vulnerabilities in real time within your test environment. Unlike SAST, which scans static code, or DAST, which probes from outside, IAST sits in the middle. It sees the live execution stack, the data flowing through it, and the security gaps that only appear when the app breathes.
Zero day risk means an exploit drops before you even know it exists. Static analysis might miss runtime issues. Dynamic testing might miss deep logic flaws. IAST finds both. It catches insecure APIs in use, SQL queries built from unsafe input, broken authentication states under load. The faster your CI/CD moves, the more that speed matters.