CWE-940: Improper Verification of Source of a Communication Channel
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Weakness ID: 940
Vulnerability Mapping:
ALLOWED
This CWE ID may be used to map to real-world vulnerabilities
Abstraction:
Base
Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.
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Description
The product establishes a communication channel to handle an incoming request that has been initiated by an actor, but it does not properly verify that the request is coming from the expected origin.
Common Consequences
 This table specifies different individual consequences
associated with the weakness. The Scope identifies the application security area that is
violated, while the Impact describes the negative technical impact that arises if an
adversary succeeds in exploiting this weakness. The Likelihood provides information about
how likely the specific consequence is expected to be seen relative to the other
consequences in the list. For example, there may be high likelihood that a weakness will be
exploited to achieve a certain impact, but a low likelihood that it will be exploited to
achieve a different impact.
| Impact |
Details |
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Gain Privileges or Assume Identity; Varies by Context; Bypass Protection Mechanism
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Scope: Access Control, Other
An attacker from an untrusted origin could successfully establish a communication channel. The attacker could then gain privileges and access unexpected functionality that was only intended for trusted sources.
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Potential Mitigations
| Phase(s) |
Mitigation |
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Architecture and Design
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Use a mechanism that can validate the identity of the source, such as a certificate, and validate the integrity of data to ensure that it cannot be modified in transit using an Adversary-in-the-Middle (AITM) attack.
When designing functionality of actions in the URL scheme, consider whether the action should be accessible to all mobile applications, or if an allowlist of applications to interface with is appropriate.
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Relationships
This table shows the weaknesses and high level categories that are related to this
weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to
similar items that may exist at higher and lower levels of abstraction. In addition,
relationships such as PeerOf, Overlaps, and CanAlsoBe are defined to show similar weaknesses that the user
may want to explore.
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Relevant to the view "Complete Weakness Hierarchy" (View-1000)
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Nature |
Type |
ID |
Name |
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ChildOf |
Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.
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346
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Origin Validation Error
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ChildOf |
Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.
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923
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Improper Restriction of Communication Channel to Intended Endpoints
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ParentOf |
Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.
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925
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Improper Verification of Intent by Broadcast Receiver
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ParentOf |
Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.
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939
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Improper Authorization in Handler for Custom URL Scheme
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Relevant to the view "Software Development" (View-699)
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Nature |
Type |
ID |
Name |
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MemberOf |
Grouping - a CWE entry that contains a set of other entries that share a common characteristic.
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417
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Communication Channel Errors
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Relevant to the view "Architectural Concepts" (View-1008)
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Nature |
Type |
ID |
Name |
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MemberOf |
Grouping - a CWE entry that contains a set of other entries that share a common characteristic.
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1014
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Identify Actors
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Modes
Of Introduction
The different Modes of Introduction provide information
about how and when this
weakness may be introduced. The Phase identifies a point in the life cycle at which
introduction
may occur, while the Note provides a typical scenario related to introduction during the
given
phase.
| Phase(s) |
Note |
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Architecture and Design
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Implementation
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REALIZATION: This weakness is caused during implementation of an architectural security tactic. |
Applicable Platforms
This listing shows possible areas for which the given
weakness could appear. These
may be for specific named Languages, Operating Systems, Architectures, Paradigms,
Technologies,
or a class of such platforms. The platform is listed along with how frequently the given
weakness appears for that instance.
| Type |
Applicable Platforms |
Notes |
| Languages |
Class: Not Language-Specific
(Undetermined Prevalence)
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| Technologies |
Class: Mobile
(Undetermined Prevalence)
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Demonstrative Examples
Example 1
This Android application will remove a user account when it receives an intent to do so:
(bad code)
Example Language: Java
IntentFilter filter = new IntentFilter("com.example.RemoveUser"); MyReceiver receiver = new MyReceiver(); registerReceiver(receiver, filter);
public class DeleteReceiver extends BroadcastReceiver { @Override public void onReceive(Context context, Intent intent) { int userID = intent.getIntExtra("userID");
destroyUserData(userID); } }
This application does not check the origin of the intent, thus allowing any malicious application to remove a user. Always check the origin of an intent, or create an allowlist of trusted applications using the manifest.xml file.
Example 2
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:
(bad code)
Example Language: Java
// Android
@Override public 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; } } }
(bad code)
Example Language: Objective-C
// 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:
(attack code)
Example Language: JavaScript
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.
Selected Observed
Examples
Note: this is a curated list of examples for users to understand the variety of ways in which this
weakness can be introduced. It is not a complete list of all CVEs that are related to this CWE entry.
| Reference |
Description |
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desktop product does not properly verify the source of a communication channel, allowing command execution
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DNS server can accept DNS updates from hosts that it did not query, leading to cache poisoning
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DNS server can accept DNS updates from hosts that it did not query, leading to cache poisoning
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DNS server caches glue records received from non-delegated name servers
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Weakness Ordinalities
| Ordinality |
Description |
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Primary
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(where the weakness exists independent of other weaknesses)
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Vulnerability Mapping Notes
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Usage
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ALLOWED
(this CWE ID may be used to map to real-world vulnerabilities)
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| Reason |
Acceptable-Use
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Rationale
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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.
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Comments
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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.
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Notes
Relationship
While many access control issues involve authenticating the user, this weakness is more about authenticating the actual source of the communication channel itself; there might not be any "user" in such cases.
Content
History
| Submissions |
| Submission Date |
Submitter |
Organization |
2014-02-13
(CWE 2.6, 2014-02-19)
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CWE Content Team |
MITRE |
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| Modifications |
| Modification Date |
Modifier |
Organization |
2026-10-28
(CWE 5.0, 2026-10-28)
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CWE Content Team |
MITRE |
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updated Common_Consequences, Description
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2026-04-30
(CWE 4.20, 2026-04-30)
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CWE Content Team |
MITRE |
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updated Observed_Examples
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2025-12-11
(CWE 4.19, 2025-12-11)
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CWE Content Team |
MITRE |
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updated Common_Consequences, Relationships, Weakness_Ordinalities
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2024-11-19
(CWE 4.16, 2024-11-19)
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CWE Content Team |
MITRE |
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updated References
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2023-06-29
(CWE 4.12, 2023-06-29)
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CWE Content Team |
MITRE |
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updated Mapping_Notes, Relationships
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2023-04-27
(CWE 4.11, 2023-04-27)
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CWE Content Team |
MITRE |
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updated Relationships
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2023-01-31
(CWE 4.10, 2023-01-31)
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CWE Content Team |
MITRE |
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updated Description, Related_Attack_Patterns
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2022-10-13
(CWE 4.9, 2022-10-13)
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CWE Content Team |
MITRE |
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updated Relationships
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2021-10-28
(CWE 4.6, 2021-10-28)
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CWE Content Team |
MITRE |
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updated Relationships
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2021-07-20
(CWE 4.5, 2021-07-20)
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CWE Content Team |
MITRE |
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updated Potential_Mitigations
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2020-06-25
(CWE 4.1, 2020-06-25)
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CWE Content Team |
MITRE |
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updated Demonstrative_Examples, Potential_Mitigations
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2020-02-24
(CWE 4.0, 2020-02-24)
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CWE Content Team |
MITRE |
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updated Applicable_Platforms, Potential_Mitigations, Relationships
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2019-06-20
(CWE 3.3, 2019-06-20)
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CWE Content Team |
MITRE |
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updated Related_Attack_Patterns
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2017-11-08
(CWE 3.0, 2017-11-08)
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CWE Content Team |
MITRE |
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updated Modes_of_Introduction, References, Relationships
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