SAST analyses the code your team wrote, looking for flaw patterns such as injection. SCA inventories the libraries you import and matches them against known vulnerabilities. They answer different questions, so one cannot stand in for the other. Most teams need both, and the order matters less than starting.
What SAST reads and reports
Static analysis examines source code or compiled code without running it. OWASP describes it as able to find certain well known flaws, like buffer overflows and SQL injection, and to point at the file and line. It can run in the editor, so a developer sees a warning while typing.
The tradeoff is noise. OWASP lists high numbers of false positives, difficulty proving a flagged issue is a real vulnerability, and trouble with code that cannot be built cleanly. It also says these tools find only a relatively small share of application security flaws, with authentication and access control problems hard to detect automatically.
What SCA reads and reports
SCA reads manifests and lockfiles, builds a list of components, and checks each against known, publicly disclosed vulnerabilities. The OWASP Dependency-Check project describes it this way: gather evidence about each dependency, work out its identity, and list associated CVE entries.
SCA findings are usually easier to act on, because the fix is often a version bump. The weakness is relevance. A library can have a known vulnerability in a function your code never calls.
A worked example
Suppose a team has a web service with a login handler that builds a query by string concatenation, and a dependency with a known deserialisation bug.
- SAST flags the concatenated query. SCA says nothing about it.
- SCA flags the dependency. SAST says nothing, because the bug lives in code you did not write.
Either tool alone leaves one real problem unreported.
How to choose which to adopt first
Pick by your biggest unknown.
- If you cannot list what you ship, start with SCA. An inventory is useful for every later decision.
- If you write a lot of custom code that handles input, start with SAST, but expect a tuning period.
- If you must answer customers about vulnerable components, SCA gives you something to show quickly.
For a longer sequencing plan, see the order to adopt scanning tools.
Click through it at your own pace, or open it full screen.
Quick check
Can SCA find a SQL injection in my own handler?
No. It reads dependencies, not your logic. That is SAST territory, and even SAST can miss it.
Why does SCA still produce noise?
A known vulnerability may sit in code your application never reaches. Reachability analysis helps separate those cases.
Sources
Last reviewed: 19 October 2026.
