CWE-348: Use of Less Trusted Source

Code Examples & CVEs

Demonstrative Examples

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.

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.

BadPHP

$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;}

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.

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.

GoodPHP

$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'];}                      ...

Observed CVE Examples (4)

CVE-2001-0860

Product uses IP address provided by a client, instead of obtaining it from the packet headers, allowing easier spoofing.

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CVE-2004-1950

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.

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CVE-2001-0908

Product logs IP address specified by the client instead of obtaining it from the packet headers, allowing information hiding.

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CVE-2006-1126

PHP application uses IP address from X-Forwarded-For HTTP header, instead of REMOTE_ADDR.

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Source-backed guidance

Additional facts reviewed against primary or authoritative security sources.

Verify controls for CWE-348 with SSDF evidence

Use NIST SSDF verification and vulnerability-response practices to detect CWE-348, Use of Less Trusted Source, throughout the product lifecycle. Derive review questions, static or dynamic checks, and negative tests from the CWE's causal behavior; define the components and lifecycle stages each check covers; and retain findings with enough evidence to distinguish the root cause from symptoms and impacts. Track escapes and false negatives, then improve the verification plan after every confirmed occurrence.

NIST SP 800-218 Secure Software Development Framework — National Institute of Standards and Technology

Make elimination of CWE-348 a product outcome

Apply CISA's Secure by Design principle of taking ownership of customer security outcomes to CWE-348, Use of Less Trusted Source. Put the weakness in the product threat model and security roadmap, fund class-level design and platform changes, prefer safe defaults and reusable guardrails, and publish measurable progress. Do not transfer the primary burden to customer configuration when the manufacturer can remove or contain the root cause in the product.

Shifting the Balance of Cybersecurity Risk: Secure by Design Software — Cybersecurity and Infrastructure Security Agency

Connect Use of Less Trusted Source to documented attack evidence

Recorded impacts include Bypass Protection Mechanism, and Gain Privileges or Assume Identity; the entry maps to CAPEC-141, CAPEC-142, CAPEC-73, and CAPEC-76; observed examples include CVE-2001-0860, CVE-2004-1950, and CVE-2001-0908. Use these source-defined anchors to turn CWE-348 into implementation, review, and verification checks for the affected component.

CWE-348: Use of Less Trusted Source — MITRE CWE

Apply precise root-cause mapping to CWE-348

Apply MITRE's full root-cause mapping guidance when using CWE-348, Use of Less Trusted Source. Separate weakness language from attacker prerequisites and technical impact, check the entry's abstraction and vulnerability-mapping notes, and prefer the most specific Base or Variant supported by the evidence. Record the rejected alternatives and require an independent review before the mapping is used for remediation trends or program metrics.

CVE to CWE Root Cause Mapping Guidance — MITRE CWE

Validate CWE-348 with root-cause mapping checks

Apply MITRE's root-cause mapping quick tips to CWE-348, Use of Less Trusted Source. Confirm the finding describes the causal weakness rather than an impact or attack pattern, compare the abstraction and mapping notes with plausible alternatives, and have a second reviewer challenge the selection. Preserve the evidence and reasoning so recurring defects can be measured against one consistent identifier.

CVE to CWE Root Cause Mapping Quick Tips — MITRE CWE

Frequently Asked Questions

What is CWE-348: Use of Less Trusted Source?+

CWE-348: Use of Less Trusted Source is a Common Weakness Enumeration (CWE) entry maintained by MITRE. 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.

What are the security consequences of Use of Less Trusted Source?+

If exploited, CWE-348 (Use of Less Trusted Source) it can compromise Access Control, leading to outcomes such as Bypass Protection Mechanism and Gain Privileges or Assume Identity.

Which programming languages are affected by Use of Less Trusted Source?+

CWE-348 commonly affects Not Language-Specific. Note that weaknesses are often language-agnostic patterns, so secure coding practices apply broadly.

What are real-world examples of Use of Less Trusted Source?+

MITRE documents real CVEs mapped to CWE-348, including CVE-2001-0860, CVE-2004-1950, CVE-2001-0908 and CVE-2006-1126. You can look up the full details of each CVE, including CVSS scores and remediation guidance, on our CVE Lookup tool.

What is the difference between a CWE and a CVE?+

A CWE (Common Weakness Enumeration) like CWE-348 describes a category of software weakness — the underlying flaw type. A CVE (Common Vulnerabilities and Exposures) identifies a specific, real-world vulnerability in a particular product. In short, a CWE is the kind of mistake, and a CVE is an instance of that mistake being found in software.

CWE-348: Use of Less Trusted Source

Technical Details

Applicable To

Security Consequences

Scope

Impact

Mitigation Strategies

Detection Methods

Code Examples & CVEs

Demonstrative Examples

Observed CVE Examples (4)

CWE Relationships

Parent Weaknesses

Source-backed guidance

Verify controls for CWE-348 with SSDF evidence

Make elimination of CWE-348 a product outcome

Connect Use of Less Trusted Source to documented attack evidence

Apply precise root-cause mapping to CWE-348

Validate CWE-348 with root-cause mapping checks

Frequently Asked Questions

Learn More