CVE-2025-4318 is a critical remote code execution (RCE) vulnerability identified in the @aws-amplify/codegen-ui NPM package—a core component used by AWS Amplify Studio for generating UI components based on declarative models. This flaw stems from the unsafe evaluation of user-defined expressions, allowing attackers to inject and execute arbitrary JavaScript code during the component rendering or build process.
📌 Background
AWS Amplify Studio is a low-code development platform that allows developers and designers to visually create full-stack web and mobile applications. It enables users to define data models, create UI components, and connect frontends to cloud-based backends. Under the hood, Amplify uses a code generation package (@aws-amplify/codegen-ui) to transform UI definitions and metadata into actual React components and code files.
To provide flexibility, the system allows expressions like labels, placeholders, or conditional logic to be defined using JavaScript strings. For example:{ "label": "`${user.firstName} ${user.lastName}`" }
While convenient, this opens a security loophole when these expressions are interpreted using eval(), Function(), or similar dynamic execution techniques without rigorous sanitization.
❗ Vulnerability Summary
⚙️ Technical Details
The vulnerability arises from how the Amplify codegen package evaluates user-supplied string expressions. These strings, meant to dynamically define properties like input labels, visibility, default values, or styles, are parsed and executed at build-time or render-time using unsafe JavaScript constructs like:new Function("context", `return ${userSuppliedExpression}`);
If a malicious actor gains access to Amplify Studio and injects a crafted expression—e.g.:"label": "`${ (() => { require('child_process').execSync('rm -rf /') })() }`"
…the malicious code is executed during the UI build process, potentially compromising the build server or CI/CD environment.
💣 Real-World Impact
- System Compromise: The attacker can execute arbitrary shell commands, exfiltrate credentials, or implant persistent backdoors during the build.
- CI/CD Exploitation: Because codegen often runs in automated pipelines, a successful attack could compromise infrastructure at scale.
- Supply Chain Risk: Generated components may be deployed downstream into production environments, creating further risk for end-users.
📅 Timeline of Disclosure
🛠️ Mitigation & Remediation
To protect against this vulnerability, organizations should take the following immediate steps:
1. Upgrade the Package
Update to @aws-amplify/codegen-ui@2.20.3 or newer. The patched version eliminates unsafe evaluation of user expressions and adds stricter checks.npm install @aws-amplify/codegen-ui@^2.20.3
2. Audit Your Environment
Review all Amplify-generated component schemas and verify that no unexpected or malicious expressions are embedded in the project history or git repositories.
3. Restrict Access
Limit permissions in Amplify Studio. Only trusted users should be allowed to modify UI components or schema definitions.
4. Secure Your CI/CD
Review build server environments for exposure. Implement sandboxing, process isolation, or static code validation to prevent arbitrary code execution during builds.
5. Monitor for Indicators of Compromise
If you’ve been running affected versions, monitor build logs, audit trails, and server telemetry for signs of exploitation.
📚 Lessons Learned
This CVE serves as a cautionary tale about the security tradeoffs of dynamic code generation in low-code platforms. Allowing unvalidated execution of strings—even for seemingly harmless UI tasks—can turn into full-scale RCE if not properly sandboxed or validated.
Developers should:
- Treat all user input, even from authenticated users, as untrusted.
- Avoid
eval()ornew Function()unless absolutely necessary—and always isolate such code in hardened, sandboxed environments. - Leverage static validation and schema-based constraints when generating dynamic UIs.
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