NULL Pointer Dereference (CWE-476) - Security Vulnerability

NULL Pointer Dereference

A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL.

NULL pointer dereferences typically cause the application to crash. In some cases, they may be exploitable for denial of service or potentially for code execution.

Prevalence

Medium

2 languages covered

Impact

Medium

Review recommended

Prevention

Documented

2 fix examples

2 Prevention

How to fix this vulnerability

🐹 Go View all Go details →

Unsafe Type Assertion Without Ok Check MEDIUM

Use the two-value form of type assertion or type switch to handle failures gracefully

+7 -3 go

- func processData(data interface{}) {
-     m := data.(map[string]interface{})
-     fmt.Println(m["key"])
+ func processData(data interface{}) error {
+     m, ok := data.(map[string]interface{})
+     if !ok {
+         return errors.New("invalid data type")
+     }
+     fmt.Println(m["key"])
+     return nil
  }

🟨 JavaScript View all JavaScript details →

Non-Null Assertion Without Null Check LOW

Replace non-null assertions (!) with explicit null checks or optional chaining

+4 -2 javascript

  interface Config {
    database?: {
      host: string;
      port: number;
    };
  }
  
  function connect(config: Config) {
-   const host = config.database!.host;
-   const port = config.database!.port;
+   if (!config.database) {
+     throw new Error('Database configuration is required');
+   }
+   const { host, port } = config.database;
    return createConnection(host, port);
  }

3 Detection

Find vulnerabilities in your code

Use Shoulder to scan your codebase for NULL Pointer Dereference patterns. 2 rules.

terminal

# Scan with Shoulder CLI
npx @shoulderdev/cli trust --cwe=476

# Or scan entire project
npx @shoulderdev/cli trust .

Detection Rules (2)

🐹 Go 1 rules

Unsafe Type Assertion Without Ok Check MEDIUM

Type assertion without two-value form can panic at runtime.

🔷 Typescript 1 rules

Non-Null Assertion Without Null Check LOW

The non-null assertion operator (!) bypasses null/undefined checks at compile time without runtime safety, causing crashes when values are unexpectedly null.

4 Warning Signs

What to watch for in code reviews

These patterns indicate potential NULL Pointer Dereference vulnerabilities. Look for these during code reviews and security audits.

🔵

Non-null assertion (!), used on '...' without explicit null/undefined check. This may cause runtime crashes if the value typescript-non-null-assertion

🔍

Scan your codebase for NULL Pointer Dereference

Shoulder CLI finds vulnerable patterns across your entire codebase.

npx shoulder trust Browse all rules