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Home > CWE List > CWE-348: Use of Less Trusted Source (4.18)
ID
CWE Glossary Definition

CWE-348: Use of Less Trusted Source

Weakness ID: 348
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 has two different sources of the same data or information, but it uses the source that has less support for verification, is less trusted, or is less resistant to attack.
Common Consequences
Section HelpThis 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

Bypass Protection Mechanism; Gain Privileges or Assume Identity

Scope: Access Control

An attacker could utilize the untrusted data source to bypass protection mechanisms and gain access to sensitive data.
Relationships
Section Help 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 and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
Relevant to the view "Research Concepts" (View-1000)
Nature Type ID Name
ChildOf Class 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. 345 Insufficient Verification of Data Authenticity
Relevant to the view "Software Development" (View-699)
Nature Type ID Name
MemberOf Category Category - a CWE entry that contains a set of other entries that share a common characteristic. 1214 Data Integrity Issues
Modes Of Introduction
Section HelpThe 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 Note
Architecture and Design
Implementation
Applicable Platforms
Section HelpThis 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.
Languages

Class: Not Language-Specific (Undetermined Prevalence)

Demonstrative Examples

Example 1


This code attempts to limit the access of a page to certain IP Addresses. It checks the 'HTTP_X_FORWARDED_FOR' header in case an authorized user is sending the request through a proxy.

(bad code)
Example Language: PHP
$requestingIP = '0.0.0.0';
if (array_key_exists('HTTP_X_FORWARDED_FOR', $_SERVER)) {
$requestingIP = $_SERVER['HTTP_X_FORWARDED_FOR'];

else{
$requestingIP = $_SERVER['REMOTE_ADDR'];
}

if(in_array($requestingIP,$ipAllowlist)){
generatePage();
return;
}
else{
echo "You are not authorized to view this page";
return;
}

The 'HTTP_X_FORWARDED_FOR' header can be user controlled and so should never be trusted. An attacker can falsify the header to gain access to the page.

This fixed code only trusts the 'REMOTE_ADDR' header and so avoids the issue:

(good code)
Example Language: PHP
$requestingIP = '0.0.0.0';
if (array_key_exists('HTTP_X_FORWARDED_FOR', $_SERVER)) {
echo "This application cannot be accessed through a proxy.";
return;

else{
$requestingIP = $_SERVER['REMOTE_ADDR'];
}
...

Be aware that 'REMOTE_ADDR' can still be spoofed. This may seem useless because the server will send the response to the fake address and not the attacker, but this may still be enough to conduct an attack. For example, if the generatePage() function in this code is resource intensive, an attacker could flood the server with fake requests using an authorized IP and consume significant resources. This could be a serious DoS attack even though the attacker would never see the page's sensitive content.



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
Product uses IP address provided by a client, instead of obtaining it from the packet headers, allowing easier spoofing.
Web product uses the IP address in the X-Forwarded-For HTTP header instead of a server variable that uses the connecting IP address, allowing filter bypass.
Product logs IP address specified by the client instead of obtaining it from the packet headers, allowing information hiding.
PHP application uses IP address from X-Forwarded-For HTTP header, instead of REMOTE_ADDR.
Memberships
Section HelpThis MemberOf Relationships table shows additional CWE Categories and Views that reference this weakness as a member. This information is often useful in understanding where a weakness fits within the context of external information sources.
Nature Type ID Name
MemberOf ViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries). 884 CWE Cross-section
MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 975 SFP Secondary Cluster: Architecture
MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 1411 Comprehensive Categorization: Insufficient Verification of Data Authenticity
Vulnerability Mapping Notes
Usage ALLOWED
(this CWE ID may be used to map to real-world vulnerabilities)
Reason Acceptable-Use

Rationale

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.

Comments

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.
Taxonomy Mappings
Mapped Taxonomy Name Node ID Fit Mapped Node Name
PLOVER Use of Less Trusted Source
Content History
Submissions
Submission Date Submitter Organization
2006年07月19日
(CWE Draft 3, 2006年07月19日) 		PLOVER
Modifications
Modification Date Modifier Organization
2024年02月29日
(CWE 4.14, 2024年02月29日) 		CWE Content Team MITRE
updated Observed_Examples
2023年06月29日 CWE Content Team MITRE
updated Mapping_Notes
2023年04月27日 CWE Content Team MITRE
updated Relationships
2023年01月31日 CWE Content Team MITRE
updated Description
2020年06月25日 CWE Content Team MITRE
updated Demonstrative_Examples
2020年02月24日 CWE Content Team MITRE
updated Relationships
2017年11月08日 CWE Content Team MITRE
updated Applicable_Platforms
2017年05月03日 CWE Content Team MITRE
updated Related_Attack_Patterns
2014年07月30日 CWE Content Team MITRE
updated Relationships
2013年07月17日 CWE Content Team MITRE
updated Relationships
2012年05月11日 CWE Content Team MITRE
updated Common_Consequences, Demonstrative_Examples, Observed_Examples, Related_Attack_Patterns, Relationships
2011年06月01日 CWE Content Team MITRE
updated Common_Consequences
2008年09月08日 CWE Content Team MITRE
updated Relationships, Taxonomy_Mappings
2008年07月01日 Eric Dalci Cigital
updated Time_of_Introduction
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Page Last Updated: September 09, 2025

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