SAST vs SCA: 5 Key Differences and How to Choose

Introducing SAST and SCA

SAST scans the proprietary source code your developers write to find internal logic flaws, while SCA scans open-source libraries and external dependencies for known, publicly disclosed vulnerabilities (CVEs).

Core differences:

Feature	SAST (Static Application Security Testing)	SCA (Software Composition Analysis)
Primary focus	Proprietary, in-house source code.	Open-source libraries and third-party dependencies.
Scan target	Custom coding flaws like SQL injections, XSS, and insecure data flows.	Known vulnerabilities (CVEs) and open-source license compliance risks.
When it runs	During development, code commits, pull requests, and CI/CD pipelines before deployment.	During builds, dependency installation, CI/CD pipelines, and continuously as new vulnerabilities are disclosed.
Typical findings	SQL injection, cross-site scripting (XSS), command injection, authentication flaws, authorization issues, insecure cryptography, and logic errors.	Vulnerable or outdated libraries, known CVEs, transitive dependency risks, deprecated packages, and license compliance issues.
How It Works	Parses syntax, data flows, and code logic against defined rules without running the application.	Identifies dependencies in manifest files and matches them against external vulnerability databases.
Remediation approach	Changing application logic and refactoring insecure code.	Patching or updating the vulnerable library to a newer, secure version.

Modern applications make extensive use of open source. According to a recent Black Duck study, 98% of applications surveyed used open source components, with an average of 1,180 open source components per application. Relying on just one of these tools creates massive blind spots in your Software Development Lifecycle (SDLC). Together, they provide a 360-degree view of your application stack.

In this article:

How SAST Works
How SCA Works
SAST vs SCA: The Key Differences
SAST Pros and Cons
SCA Pros and Cons
SCA vs. SAST: How to Choose

How SAST Works

SAST operates by scanning the application’s source code, bytecode, or binaries for patterns that match known security vulnerabilities. It parses the code and applies rules or heuristics to identify risky coding practices, insecure function calls, or insufficient input validation. The process can be automated and integrated into development environments, allowing for frequent and consistent analysis throughout the software development lifecycle.

Once a scan is complete, SAST tools generate detailed reports highlighting the location and nature of vulnerabilities. These reports often include guidance for remediation, helping developers understand why an issue is a security risk and how it can be resolved. By providing actionable feedback early, SAST helps reduce technical debt and ensures that security is an ongoing part of the development process rather than an afterthought.

How SCA Works

SCA tools analyze the manifest files, dependency trees, and sometimes the actual codebase to enumerate all third-party components in an application. They then compare these components against vulnerability databases like the National Vulnerability Database (NVD) or proprietary sources to identify known security issues. The tools also check for outdated or deprecated libraries and flag potential licensing conflicts that could affect distribution or legal compliance.

Once the analysis is complete, SCA tools produce reports detailing each dependency, its version, any associated vulnerabilities, and licensing status. These reports allow teams to prioritize remediation efforts, such as upgrading to secure versions or replacing problematic libraries. By automating the tracking of third-party components, SCA helps organizations reduce the risk of supply chain attacks and maintain a secure software ecosystem.

SAST vs SCA: The Key Differences

While both SAST and SCA contribute to software security, their approaches and areas of focus are distinct. Understanding these differences is crucial for building a comprehensive application security strategy. The following sections break down the primary focus, scan targets, timing, typical findings, and remediation approaches of each technology.

1. Primary Focus

SAST’s primary focus is on the security of the application’s custom source code. It aims to identify vulnerabilities introduced by developers, such as logic errors, insecure coding patterns, or improper handling of user input. By examining the code directly, SAST ensures that the core logic of the application is robust against common attack vectors.

SCA is centered around the security and compliance of third-party and open-source components used within an application. Its goal is to detect known vulnerabilities, outdated dependencies, and license risks in external libraries. SCA helps organizations manage the risks associated with integrating external code, which can be a significant portion of modern software.

2. Scan Target

SAST targets the application’s internal codebase, which includes source code, bytecode, or binaries, depending on the tool and programming language. It does not analyze external dependencies or libraries unless they are included as source code within the project. The focus remains strictly on the proprietary code written by the development team.

SCA scans the manifest files, dependency lists, and sometimes the compiled application to identify all third-party components in use. Its analysis is limited to these external packages, examining their versions, known vulnerabilities, and licensing details. SCA does not evaluate the custom logic of the application itself, but rather what is brought in from external sources.

3. When It Runs

SAST is typically integrated early in the development process and can run continuously as developers write and commit code. It is often configured to trigger scans upon code check-ins, pull requests, or as part of the build pipeline, providing immediate feedback to developers and allowing issues to be fixed before deployment.

SCA is usually run during the build or packaging stage, when the application’s dependency tree is finalized. However, it can also be integrated into continuous integration/continuous deployment (CI/CD) pipelines to monitor for new vulnerabilities in dependencies as they are discovered. This ensures that both new and existing projects remain protected against emerging threats.

4. Typical Findings

SAST tools commonly identify issues such as SQL injection, cross-site scripting (XSS), buffer overflows, and insecure authentication or authorization logic. These findings are specific to the code written by the development team and relate to how the application handles data, user input, and critical operations.

SCA tools report on known vulnerabilities in third-party libraries, such as critical CVEs, outdated dependencies, and license compliance problems. The findings are tied to the external packages included in the application, highlighting risks introduced by software that the organization did not write but relies upon.

5. Remediation Approach

Remediating SAST findings typically involves developers modifying their source code to address the identified vulnerabilities. This may include rewriting insecure code, adding proper validation, or adopting secure coding practices. Developers need to understand the root cause of each issue to ensure effective and lasting fixes.

SCA remediation focuses on updating, replacing, or removing vulnerable or non-compliant dependencies. This often involves upgrading to secure versions of libraries, switching to alternative packages, or resolving licensing conflicts. The process is generally more about dependency management than code changes, though updates can sometimes require code adjustments for compatibility.

Related content: Read our guide to cloud application security.

SAST Pros and Cons

SAST is designed to improve the security of an application’s proprietary code by identifying vulnerabilities before the software reaches production. It is most effective when integrated into the development workflow, where developers can address issues as they write and review code. At the same time, organizations should understand its limitations and use it alongside other security testing methods.

Pros

Finds vulnerabilities early in the development lifecycle: SAST identifies security issues during coding, code reviews, or CI/CD builds, allowing developers to fix problems before they become more expensive and time-consuming to resolve later in testing or production.
Analyzes custom application code in depth: Because it inspects source code, bytecode, or binaries directly, SAST can detect vulnerabilities introduced by developers, including insecure input validation, authentication flaws, hardcoded secrets, and unsafe API usage.
Provides detailed remediation guidance: Most SAST tools report the exact file, function, and line where an issue occurs, along with an explanation of the vulnerability and recommendations for fixing it. This reduces the time required to investigate findings.
Supports secure development practices: Continuous feedback encourages developers to adopt secure coding standards and avoid introducing common vulnerabilities into new code. Over time, this can improve the overall security quality of the codebase.
Integrates well into developer workflows: Modern SAST tools can run inside IDEs, source control platforms, and CI/CD pipelines, enabling automated security testing without requiring a separate manual review process for every code change.
Helps meet regulatory and compliance requirements: Many security frameworks and industry standards recommend or require static code analysis as part of a secure software development lifecycle, making SAST useful for compliance efforts.

Cons

Cannot assess third-party dependencies: SAST focuses on proprietary application code and generally does not identify vulnerabilities in open-source libraries or external packages. Organizations need SCA or similar tools to cover this gap.
May generate false positives: Static analysis relies on rules and pattern matching, which can sometimes flag code that is not actually exploitable. Security teams and developers may need to validate findings before remediation.
Cannot detect runtime-specific vulnerabilities: Since SAST analyzes code without executing the application, it cannot identify issues that depend on runtime behavior, server configuration, authentication flows, or interactions between multiple components.
Requires access to the application’s code: Unlike black-box testing methods, SAST cannot be used on applications where the source code or compiled artifacts are unavailable.
Can require significant configuration and maintenance: Large or complex projects often need customized rules, exclusions, and tuning to reduce noise and improve the relevance of scan results.
May increase build times for large codebases: Comprehensive scans can take considerable time in large enterprise applications, requiring teams to balance scan frequency with development velocity.

SCA Pros and Cons

SCA focuses on securing the software supply chain by identifying vulnerabilities, outdated packages, and licensing issues in third-party components. Since modern applications often rely heavily on open-source software, SCA has become an essential part of application security. However, it complements rather than replaces code analysis tools like SAST.

Pros

Identifies known vulnerabilities in third-party components: SCA compares project dependencies against public and commercial vulnerability databases to detect libraries affected by known CVEs and other published security issues.
Provides complete visibility into software dependencies: It creates an inventory of all direct and transitive dependencies, helping organizations understand exactly which external components are included in each application.
Detects outdated or unsupported packages: SCA highlights libraries that are no longer maintained or have newer secure versions available, allowing teams to reduce long-term security and maintenance risks.
Helps maintain license compliance: In addition to security analysis, SCA identifies software licenses associated with dependencies and flags licenses that may conflict with organizational policies or commercial distribution requirements.
Supports continuous monitoring of the software supply chain: Many SCA tools continue monitoring deployed applications and alert teams when new vulnerabilities are disclosed for existing dependencies, even if the application itself has not changed.
Improves dependency management across projects: Organizations can standardize approved libraries, reduce duplicate packages, and gain better visibility into software supply chain risks across multiple development teams.

Cons

Cannot identify vulnerabilities in custom application code: SCA only evaluates external dependencies and does not analyze the security of business logic, input validation, or other code written by developers.
Relies on known vulnerability databases: If a vulnerability has not yet been publicly disclosed or added to vulnerability databases, SCA tools typically cannot detect it.
Can produce a high volume of findings: Applications with many dependencies may generate hundreds of alerts, making it necessary to prioritize remediation based on exploitability, severity, and business impact.
Dependency updates may require additional development work: Upgrading vulnerable libraries can introduce breaking API changes, compatibility issues, or unexpected behavior that requires testing and code modifications.
May not detect unused vulnerable code paths: Some tools report vulnerabilities simply because a dependency is present, even if the vulnerable functionality is never used by the application. Additional analysis may be needed to determine actual risk.
Provides limited insight into exploitability: SCA identifies vulnerable packages but rarely determines whether the vulnerable code is reachable, and almost never whether it is exploitable. Reachability is only the first check. A reachable function still cannot be exploited unless the vulnerability’s other prerequisites are met in that environment.

SCA vs. SAST: How to Choose

Choosing between SCA and SAST depends on what risk you need to find. SAST is better for issues in custom code, while SCA is better for risks in open-source and third-party components. Most teams need both, because they cover different parts of the application.

Considerations

Use SAST when custom code is the main concern: SAST helps find vulnerabilities caused by developer-written code, such as injection flaws, insecure logic, weak validation, and unsafe data handling.
Use SCA when third-party dependencies are the main concern: SCA identifies vulnerable packages, outdated libraries, transitive dependencies, and license risks introduced through external components.
Consider where risk enters the application: If most security issues come from new features and business logic, prioritize SAST. If the application relies heavily on open-source packages, prioritize SCA.
Match the tool to the development stage: SAST works best early in coding and pull requests. SCA is most useful during dependency installation, builds, and release checks.
Evaluate remediation effort: SAST findings usually require code changes. SCA findings often require package upgrades, dependency replacement, or license review.
Account for compliance needs: SAST can support secure coding and application security requirements. SCA is important for software supply chain security, open-source governance, and license compliance.
Use both for broader coverage: SAST and SCA are not replacements for each other. Using them together gives better visibility into both proprietary code risks and third-party component risks.
Plan for what happens after the scan: Neither SAST nor SCA tells you whether a finding is exploitable in your environment. Both produce lists that still need investigating, so factor in how you will validate findings before they reach a developer.

Covering Both SAST and SCA with Maze Code

Because SAST and SCA protect different parts of the same application, most teams end up running two tools that each produce a separate backlog of findings with no easy way to tell which ones matter. Maze Code takes a different approach. It uses AI agents to investigate every vulnerability in both the third-party dependencies you rely on (AI-SCA) and the code your team writes (AI-SAST), then proves which findings are actually exploitable in your environment and routes a verified fix to the right developer. Both run on a single engine, adding the investigation layer that traditional SAST and SCA tools skip.

Key capabilities of Maze Code:

AI-SCA for dependencies: Finds every vulnerable dependency and prioritizes the ones that create real risk for your organization, using AI-built call graphs that pick up where traditional reachability methods stop and determining exploitability with context from your code and cloud.
AI-SAST for custom code: Rather than matching your code against known patterns, Maze agents understand what the code actually does, surfacing novel vulnerabilities and complex business-logic flaws other tools miss, then evaluating which are exploitable in your environment.
Exploitability over reachability: Traces the full call chain, however many hops deep a vulnerability sits, and checks your runtime and cloud to prove what is genuinely exploitable, closing findings that are reachable but not exploitable before they reach your team.
Automated remediation to the right owner: Writes fixes that match your code, identifies the developer who owns it, and ships the PR directly to them, recommending a mitigation when no logical fix exists.
One investigation across code and cloud: Runs on the same platform as Maze Cloud, so code context enriches cloud findings and cloud context enriches code findings, leaving you with one unified ticket per issue instead of multiple.
Fits your existing workflow and scanners: Ships with its own scanner but can also ingest and dedupe findings from the tools you already run, operating inside your CI/CD pipeline (GitHub Actions, GitLab CI, CircleCI) and surfacing findings right at the pull request.

Learn how Maze investigates, proves, and fixes both code and dependency vulnerabilities. Explore Maze Code.