The product uses a fixed or controlled search path to find resources, but one or more locations in that path can be under the control of unintended actors.

Although this weakness can occur with any type of resource, it is frequently introduced when a product uses a directory search path to find executables or code libraries, but the path contains a directory that can be modified by an attacker, such as "/tmp" or the current working directory.
In Windows-based systems, when the LoadLibrary or LoadLibraryEx function is called with a DLL name that does not contain a fully qualified path, the function follows a search order that includes two path elements that might be uncontrolled:

the directory from which the program has been loaded
the current working directory

In some cases, the attack can be conducted remotely, such as when SMB or WebDAV network shares are used.
One or more locations in that path could include the Windows drive root or its subdirectories. This often exists in Linux-based code assuming the controlled nature of the root directory (/) or its subdirectories (/etc, etc), or a code that recursively accesses the parent directory. In Windows, the drive root and some of its subdirectories have weak permissions by default, which makes them uncontrolled.
In some Unix-based systems, a PATH might be created that contains an empty element, e.g. by splicing an empty variable into the PATH. This empty element can be interpreted as equivalent to the current working directory, which might be an untrusted search element.
In software package management frameworks (e.g., npm, RubyGems, or PyPi), the framework may identify dependencies on third-party libraries or other packages, then consult a repository that contains the desired package. The framework may search a public repository before a private repository. This could be exploited by attackers by placing a malicious package in the public repository that has the same name as a package from the private repository. The search path might not be directly under control of the developer relying on the framework, but this search order effectively contains an untrusted element.

Primary

DLL preloading
This term is one of several that are used to describe exploitation of untrusted search path elements in Windows systems, which received wide attention in August 2010. From a weakness perspective, the term is imprecise because it can apply to both CWE-426 and CWE-427.

Binary planting
This term is one of several that are used to describe exploitation of untrusted search path elements in Windows systems, which received wide attention in August 2010. From a weakness perspective, the term is imprecise because it can apply to both CWE-426 and CWE-427.

Insecure library loading
This term is one of several that are used to describe exploitation of untrusted search path elements in Windows systems, which received wide attention in August 2010. From a weakness perspective, the term is imprecise because it can apply to both CWE-426 and CWE-427.

Dependency confusion
As of February 2021, this term is used to describe CWE-427 in the context of managing installation of software package dependencies, in which attackers release packages on public sites where the names are the same as package names used by private repositories, and the search for the dependent package tries the public site first, downloading untrusted code. It may also be referred to as a "substitution attack."

Implementation

Confidentiality
Integrity
Availability
Execute Unauthorized Code or Commands

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
Implementation
Attack Surface Reduction
Hard-code the search path to a set of known-safe values (such as system directories), or only allow them to be specified by the administrator in a configuration file. Do not allow these settings to be modified by an external party. Be careful to avoid related weaknesses such as CWE-426 and CWE-428.

Implementation
Attack Surface Reduction
When invoking other programs, specify those programs using fully-qualified pathnames. While this is an effective approach, code that uses fully-qualified pathnames might not be portable to other systems that do not use the same pathnames. The portability can be improved by locating the full-qualified paths in a centralized, easily-modifiable location within the source code, and having the code refer to these paths.

Implementation
Attack Surface Reduction
Remove or restrict all environment settings before invoking other programs. This includes the PATH environment variable, LD_LIBRARY_PATH, and other settings that identify the location of code libraries, and any application-specific search paths.

Implementation
Check your search path before use and remove any elements that are likely to be unsafe, such as the current working directory or a temporary files directory. Since this is a denylist approach, it might not be a complete solution.

Implementation
Use other functions that require explicit paths. Making use of any of the other readily available functions that require explicit paths is a safe way to avoid this problem. For example, system() in C does not require a full path since the shell can take care of finding the program using the PATH environment variable, while execl() and execv() require a full path.

The following code is from a web application that allows users access to an interface through which they can update their password on the system. In this environment, user passwords can be managed using the Network Information System (NIS), which is commonly used on UNIX systems. When performing NIS updates, part of the process for updating passwords is to run a make command in the /var/yp directory. Performing NIS updates requires extra privileges.

...System.Runtime.getRuntime().exec("make");...

The problem here is that the program does not specify an absolute path for make and does not clean its environment prior to executing the call to Runtime.exec(). If an attacker can modify the $PATH variable to point to a malicious binary called make and cause the program to be executed in their environment, then the malicious binary will be loaded instead of the one intended. Because of the nature of the application, it runs with the privileges necessary to perform system operations, which means the attacker's make will now be run with these privileges, possibly giving the attacker complete control of the system.

In versions of Go prior to v1.19, the LookPath function would follow the conventions of the runtime OS and look for a program in the directiories listed in the current path [REF-1325].
Therefore, Go would prioritize searching the current directory when the provided command name does not contain a directory separator and continued to search for programs even when the specified program name is empty.
Consider the following where an application executes a git command to run on the system.

func ExecuteGitCommand(name string, arg []string) error {

c := exec.Command(name, arg...)
var err error
c.Path, err = exec.LookPath(name)
if err != nil {

return err

}
}

An attacker could create a malicious repository with a file named ..exe and another file named git.exe. If git.exe is not found in the system PATH, then ..exe would execute [REF-1326].

In February 2021 [REF-1169], a researcher was able to demonstrate the ability to breach major technology companies by using "dependency confusion" where the companies would download and execute untrusted packages.
The researcher discovered the names of some internal, private packages by looking at dependency lists in public source code, such as package.json. The researcher then created new, untrusted packages with the same name as the internal packages, then uploaded them to package hosting services. These services included the npm registry for Node, PyPi for Python, and RubyGems. In affected companies, their dependency resolution would search the public hosting services first before consulting their internal service, causing the untrusted packages to be automatically downloaded and executed.

CVE-2023-25815
chain: a change in an underlying package causes the gettext function to use implicit initialization with a hard-coded path (CWE-1419) under the user-writable C:\ drive, introducing an untrusted search path element (CWE-427) that enables spoofing of messages.
https://www.cve.org/CVERecord?id=CVE-2023-25815

CVE-2022-4826
Go-based git extension on Windows can search for and execute a malicious "..exe" in a repository because Go searches the current working directory if git.exe is not found in the PATH
https://www.cve.org/CVERecord?id=CVE-2022-4826

CVE-2020-26284
A Static Site Generator built in Go, when running on Windows, searches the current working directory for a command, possibly allowing code execution using a malicious .exe or .bat file with the name being searched
https://www.cve.org/CVERecord?id=CVE-2020-26284

CVE-2022-24765
Windows-based fork of git creates a ".git" folder in the C: drive, allowing local attackers to create a .git folder with a malicious config file
https://www.cve.org/CVERecord?id=CVE-2022-24765

CVE-2019-1552
SSL package searches under "C:/usr/local" for configuration files and other critical data, but C:/usr/local might be world-writable.
https://www.cve.org/CVERecord?id=CVE-2019-1552

CVE-2010-3402
"DLL hijacking" issue in document editor.
https://www.cve.org/CVERecord?id=CVE-2010-3402

CVE-2010-3397
"DLL hijacking" issue in encryption software.
https://www.cve.org/CVERecord?id=CVE-2010-3397

CVE-2010-3138
"DLL hijacking" issue in library used by multiple media players.
https://www.cve.org/CVERecord?id=CVE-2010-3138

CVE-2010-3152
"DLL hijacking" issue in illustration program.
https://www.cve.org/CVERecord?id=CVE-2010-3152

CVE-2010-3147
"DLL hijacking" issue in address book.
https://www.cve.org/CVERecord?id=CVE-2010-3147

CVE-2010-3135
"DLL hijacking" issue in network monitoring software.
https://www.cve.org/CVERecord?id=CVE-2010-3135

CVE-2010-3131
"DLL hijacking" issue in web browser.
https://www.cve.org/CVERecord?id=CVE-2010-3131

CVE-2010-1795
"DLL hijacking" issue in music player/organizer.
https://www.cve.org/CVERecord?id=CVE-2010-1795

CVE-2002-1576
Product uses the current working directory to find and execute a program, which allows local users to gain privileges by creating a symlink that points to a malicious version of the program.
https://www.cve.org/CVERecord?id=CVE-2002-1576

CVE-1999-1461
Product trusts the PATH environmental variable to find and execute a program, which allows local users to obtain root access by modifying the PATH to point to a malicous version of that program.
https://www.cve.org/CVERecord?id=CVE-1999-1461

CVE-1999-1318
Software uses a search path that includes the current working directory (.), which allows local users to gain privileges via malicious programs.
https://www.cve.org/CVERecord?id=CVE-1999-1318

CVE-2003-0579
Admin software trusts the user-supplied -uv.install command line option to find and execute the uv.install program, which allows local users to gain privileges by providing a pathname that is under control of the user.
https://www.cve.org/CVERecord?id=CVE-2003-0579

CVE-2000-0854
When a document is opened, the directory of that document is first used to locate DLLs , which could allow an attacker to execute arbitrary commands by inserting malicious DLLs into the same directory as the document.
https://www.cve.org/CVERecord?id=CVE-2000-0854

CVE-2001-0943
Database trusts the PATH environment variable to find and execute programs, which allows local users to modify the PATH to point to malicious programs.
https://www.cve.org/CVERecord?id=CVE-2001-0943

CVE-2001-0942
Database uses an environment variable to find and execute a program, which allows local users to execute arbitrary programs by changing the environment variable.
https://www.cve.org/CVERecord?id=CVE-2001-0942

CVE-2001-0507
Server uses relative paths to find system files that will run in-process, which allows local users to gain privileges via a malicious file.
https://www.cve.org/CVERecord?id=CVE-2001-0507

CVE-2002-2017
Product allows local users to execute arbitrary code by setting an environment variable to reference a malicious program.
https://www.cve.org/CVERecord?id=CVE-2002-2017

CVE-1999-0690
Product includes the current directory in root's PATH variable.
https://www.cve.org/CVERecord?id=CVE-1999-0690

CVE-2001-0912
Error during packaging causes product to include a hard-coded, non-standard directory in search path.
https://www.cve.org/CVERecord?id=CVE-2001-0912

CVE-2001-0289
Product searches current working directory for configuration file.
https://www.cve.org/CVERecord?id=CVE-2001-0289

CVE-2005-1705
Product searches current working directory for configuration file.
https://www.cve.org/CVERecord?id=CVE-2005-1705

CVE-2005-1307
Product executable other program from current working directory.
https://www.cve.org/CVERecord?id=CVE-2005-1307

CVE-2002-2040
Untrusted path.
https://www.cve.org/CVERecord?id=CVE-2002-2040

CVE-2005-2072
Modification of trusted environment variable leads to untrusted path vulnerability.
https://www.cve.org/CVERecord?id=CVE-2005-2072

CVE-2005-1632
Product searches /tmp for modules before other paths.
https://www.cve.org/CVERecord?id=CVE-2005-1632

Program Invocation
Code Libraries

System Process

Uncontrolled Search Path Element

Allowed-with-Review
This CWE entry is often confused with another closely-related entry about search paths.
CWE-426 and CWE-427 are often misused because they both mention search paths, although CWE-426 is focused on attacker control of the search path itself, while CWE-427 applies when the attacker cannot modify the search path but can write to one of the locations specified in the search path. Also, this entry is classified in a part of CWE's hierarchy that does not have sufficiently low-level coverage, which might reflect a lack of classification-oriented weakness research in the software security community. Conduct careful root cause analysis to determine the original mistake that led to this weakness. If closer analysis reveals that this weakness is appropriate, then this might be the best available CWE to use for mapping. If no other option is available, then it is acceptable to map to this CWE.

Unlike untrusted search path (CWE-426), which inherently involves control over the definition of a control sphere (i.e., modification of a search path), this entry concerns a fixed control sphere in which some part of the sphere may be under attacker control (i.e., the search path cannot be modified by an attacker, but one element of the path can be under attacker control).
This weakness is not a clean fit under CWE-668 or CWE-610, which suggests that the control sphere model might need enhancement or clarification.

PLOVER
2006-07-19
Draft 3
2006-07-19

Eric Dalci
Cigital
2008-07-01
updated Potential_Mitigations, Time_of_Introduction

CWE Content Team
MITRE
2008-09-08
updated Relationships, Observed_Example, Other_Notes, Taxonomy_Mappings

CWE Content Team
MITRE
2009-07-27
updated Description, Maintenance_Notes, Observed_Examples, Other_Notes, Potential_Mitigations, Relationships

CWE Content Team
MITRE
2010-09-27
updated Alternate_Terms, Applicable_Platforms, Description, Maintenance_Notes, Observed_Examples, References, Relationship_Notes, Relationships

CWE Content Team
MITRE
2011-03-29
updated Potential_Mitigations

CWE Content Team
MITRE
2011-06-01
updated Common_Consequences

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

CWE Content Team
MITRE
2014-02-18
updated Demonstrative_Examples, Observed_Examples, Potential_Mitigations

CWE Content Team
MITRE
2014-07-30
updated Relationships

CWE Content Team
MITRE
2015-12-07
updated Relationships

CWE Content Team
MITRE
2019-01-03
updated Related_Attack_Patterns

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

CWE Content Team
MITRE
2020-02-24
updated Relationships

CWE Content Team
MITRE
2020-06-25
updated Potential_Mitigations

CWE Content Team
MITRE
2021-03-15
updated Alternate_Terms, Description, Maintenance_Notes, References, Theoretical_Notes

CWE Content Team
MITRE
2022-04-28
updated Demonstrative_Examples

CWE Content Team
MITRE
2022-10-13
updated Observed_Examples

CWE Content Team
MITRE
2023-01-31
updated Description, Observed_Examples, References

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

CWE Content Team
MITRE
2023-06-29
updated Mapping_Notes

CWE Content Team
MITRE
2023-10-26
updated Observed_Examples

CWE Content Team
MITRE
2025-04-03
4.17
2025-04-03
updated Mapping_Notes

CWE Content Team
MITRE
2025-09-09
4.18
2025-09-09
updated Affected_Resources, Functional_Areas, References

CWE Content Team
MITRE
2025-12-11
4.19
2025-12-11
updated Applicable_Platforms, Relationships, Weakness_Ordinalities

Anonymous External Contributor
2022-05-24
provided observed examples and descriptions for Windows drive root