The product provides an Applications Programming Interface (API) or similar interface for interaction with external actors, but the interface includes a dangerous method or function that is not properly restricted.

This weakness can lead to a wide variety of resultant weaknesses, depending on the behavior of the exposed method. It can apply to any number of technologies and approaches, such as ActiveX controls, Java functions, IOCTLs, and so on.
The exposure can occur in a few different ways:

The function/method was never intended to be exposed to outside actors.
The function/method was only intended to be accessible to a limited set of actors, such as Internet-based access from a single web site.

Primary

Architecture and Design

Implementation

Low

Integrity
Confidentiality
Availability
Access Control
Other
Gain Privileges or Assume Identity
Read Application Data
Modify Application Data
Execute Unauthorized Code or Commands
Other
Exposing critical functionality essentially provides an attacker with the privilege level of the exposed functionality. This could result in the modification or exposure of sensitive data or possibly even execution of arbitrary code.

Automated Static Analysis
Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)
High

Architecture and Design
If you must expose a method, make sure to perform input validation on all arguments, limit access to authorized parties, and protect against all possible vulnerabilities.

Architecture and Design
Implementation
Attack Surface Reduction

Identify all exposed functionality. Explicitly list all functionality that must be exposed to some user or set of users. Identify which functionality may be:

accessible to all users
restricted to a small set of privileged users
prevented from being directly accessible at all

Ensure that the implemented code follows these expectations. This includes setting the appropriate access modifiers where applicable (public, private, protected, etc.) or not marking ActiveX controls safe-for-scripting.

In the following Java example the method removeDatabase will delete the database with the name specified in the input parameter.

public void removeDatabase(String databaseName) {
try {
Statement stmt = conn.createStatement();stmt.execute("DROP DATABASE " + databaseName);

} catch (SQLException ex) {...}
}

The method in this example is declared public and therefore is exposed to any class in the application. Deleting a database should be considered a critical operation within an application and access to this potentially dangerous method should be restricted. Within Java this can be accomplished simply by declaring the method private thereby exposing it only to the enclosing class as in the following example.

private void removeDatabase(String databaseName) {
try {
Statement stmt = conn.createStatement();stmt.execute("DROP DATABASE " + databaseName);

} catch (SQLException ex) {...}}

These Android and iOS applications intercept URL loading within a WebView and perform special actions if a particular URL scheme is used, thus allowing the Javascript within the WebView to communicate with the application:

// Android
@Overridepublic boolean shouldOverrideUrlLoading(WebView view, String url){
if (url.substring(0,14).equalsIgnoreCase("examplescheme:")){if(url.substring(14,25).equalsIgnoreCase("getUserInfo")){writeDataToView(view, UserData);return false;}else{return true;}}
}

// iOS
-(BOOL) webView:(UIWebView *)exWebView shouldStartLoadWithRequest:(NSURLRequest *)exRequest navigationType:(UIWebViewNavigationType)exNavigationType{
NSURL *URL = [exRequest URL];if ([[URL scheme] isEqualToString:@"exampleScheme"]){
NSString *functionString = [URL resourceSpecifier];if ([functionString hasPrefix:@"specialFunction"]){

// Make data available back in webview.
UIWebView *webView = [self writeDataToView:[URL query]];
}return NO;
}return YES;
}

A call into native code can then be initiated by passing parameters within the URL:

window.location = examplescheme://method?parameter=value

Because the application does not check the source, a malicious website loaded within this WebView has the same access to the API as a trusted site.

This application uses a WebView to display websites, and creates a Javascript interface to a Java object to allow enhanced functionality on a trusted website:

public class WebViewGUI extends Activity {
WebView mainWebView;
public void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);mainWebView = new WebView(this);mainWebView.getSettings().setJavaScriptEnabled(true);mainWebView.addJavascriptInterface(new JavaScriptInterface(), "userInfoObject");mainWebView.loadUrl("file:///android_asset/www/index.html");setContentView(mainWebView);}
final class JavaScriptInterface {
JavaScriptInterface () {}
public String getUserInfo() {return currentUser.Info();}
}
}

Before Android 4.2 all methods, including inherited ones, are exposed to Javascript when using addJavascriptInterface(). This means that a malicious website loaded within this WebView can use reflection to acquire a reference to arbitrary Java objects. This will allow the website code to perform any action the parent application is authorized to.
For example, if the application has permission to send text messages:

<script>userInfoObject.getClass().forName('android.telephony.SmsManager').getMethod('getDefault',null).sendTextMessage(attackNumber, null, attackMessage, null, null);</script>

This malicious script can use the userInfoObject object to load the SmsManager object and send arbitrary text messages to any recipient.

After Android 4.2, only methods annotated with @JavascriptInterface are available in JavaScript, protecting usage of getClass() by default, as in this example:

final class JavaScriptInterface {
JavaScriptInterface () { }
@JavascriptInterfacepublic String getUserInfo() {return currentUser.Info();}
}

This code is not vulnerable to the above attack, but still may expose user info to malicious pages loaded in the WebView. Even malicious iframes loaded within a trusted page may access the exposed interface:

<script>var info = window.userInfoObject.getUserInfo();sendUserInfo(info);</script>

This malicious code within an iframe is able to access the interface object and steal the user's data.

CVE-2007-6382
arbitrary Java code execution via exposed method
https://www.cve.org/CVERecord?id=CVE-2007-6382

CVE-2007-1112
security tool ActiveX control allows download or upload of files
https://www.cve.org/CVERecord?id=CVE-2007-1112

Allowed
This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

Under-reported and under-studied. This weakness could appear in any technology, language, or framework that allows the programmer to provide a functional interface to external parties, but it is not heavily reported. In 2007, CVE began showing a notable increase in reports of exposed method vulnerabilities in ActiveX applications, as well as IOCTL access to OS-level resources. These weaknesses have been documented for Java applications in various secure programming sources, but there are few reports in CVE, which suggests limited awareness in most parts of the vulnerability research community.

CWE Content Team
MITRE
2008-11-24
1.1
2008-11-24

CWE Content Team
MITRE
2009-01-12
updated Name

CWE Content Team
MITRE
2009-07-27
updated Relationships

CWE Content Team
MITRE
2009-12-28
updated Applicable_Platforms, Likelihood_of_Exploit

CWE Content Team
MITRE
2010-02-16
updated Common_Consequences, Demonstrative_Examples, Potential_Mitigations, References, Related_Attack_Patterns, Relationships

CWE Content Team
MITRE
2010-04-05
updated Demonstrative_Examples, Related_Attack_Patterns

CWE Content Team
MITRE
2010-06-21
updated Common_Consequences

CWE Content Team
MITRE
2011-06-01
updated Common_Consequences

CWE Content Team
MITRE
2012-05-11
updated Relationships

CWE Content Team
MITRE
2014-02-18
updated Demonstrative_Examples

CWE Content Team
MITRE
2014-07-30
updated Relationships

CWE Content Team
MITRE
2015-12-07
updated Relationships

CWE Content Team
MITRE
2017-11-08
updated Likelihood_of_Exploit, References, Relationships

CWE Content Team
MITRE
2019-06-20
updated Relationships

CWE Content Team
MITRE
2020-02-24
updated Relationships

CWE Content Team
MITRE
2023-01-31
updated Description, Related_Attack_Patterns, Relationships

CWE Content Team
MITRE
2023-04-27
updated Detection_Factors, References, Relationships

CWE Content Team
MITRE
2023-06-29
updated Mapping_Notes

CWE Content Team
MITRE
2025-12-11
4.19
2025-12-11
updated Relationships

Exposed Insecure Method or Function