The product opens a file or directory, but it does not properly prevent the name from being associated with a junction or mount point to a destination that is outside of the intended control sphere.

Depending on the intended action
being performed, this could allow an
attacker to cause the product to read,
write, delete, or otherwise operate on
unauthorized files.
In Windows, NTFS5 allows for file
system objects called reparse points.
Applications can create a hard link from one
directory to another directory, called a
junction point. They can also create a
mapping from a directory to a drive letter,
called a mount point. If a file is used by a
privileged program, but it can be replaced
with a hard link to a sensitive file (e.g.,
AUTOEXEC.BAT), an attacker could excalate
privileges. When the process opens the file,
the attacker can assume the privileges of
that process, tricking the privileged
process to read, modify, or delete the
sensitive file, preventing the program from
accurately processing data. Note that one
can also point to registries and
semaphores.

Primary

Resultant

Implementation
The developer might not consider that when a program in Windows operates with different permissions than the executing user, the use of links, mount points, and junctions might cause the program to access files or directories that are outside of the intended storage location.

Confidentiality
Read Files or Directories
Read arbitrary files by replacing a user-controlled folder with a mount point and additional hard links.

Integrity
Modify Files or Directories
Modify an arbitrary file by replacing the rollback files in installer directories, as they can have the installer execute those rollbacks.

Availability
Modify Files or Directories
Even if there is no control of contents, an arbitrary file delete or overwrite (when running as SYSTEM or admin) can be used for a permanent system denial-of-service, e.g. by deleting a startup configuration file that prevents the service from starting.

Architecture and Design
Separation of Privilege
When designing software that will have different rights than the executer, the software should check that files that it is interacting with are not improper hard links or mount points. One way to do this in Windows is to use the functionality embedded in the following command: "dir /al /s /b" or, in PowerShell, use LinkType as a filter. In addition, some software uses authentication via signing to ensure that the file is the correct one to use. Make checks atomic with the file action, otherwise a TOCTOU weakness (CWE-367) can be introduced.

CVE-2021-26426
Privileged service allows attackers to delete unauthorized files using a directory junction, leading to arbitrary code execution as SYSTEM.
https://www.cve.org/CVERecord?id=CVE-2021-26426

CVE-2020-0863
By creating a mount point and hard links, an attacker can abuse a service to allow users arbitrary file read permissions.
https://www.cve.org/CVERecord?id=CVE-2020-0863

CVE-2019-1161
Chain: race condition (CWE-362) in anti-malware product allows deletion of files by creating a junction (CWE-1386) and using hard links during the time window in which a temporary file is created and deleted.
https://www.cve.org/CVERecord?id=CVE-2019-1161

CVE-2014-0568
Escape from sandbox for document reader by using a mountpoint [REF-1264]
https://www.cve.org/CVERecord?id=CVE-2014-0568

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.

Symbolic links, hard links, junctions, and mount points can be confusing terminology, as there are differences in how they operate between UNIX-based systems and Windows, and there are interactions between them.
This entry is still under development and will continue to see updates and content improvements.

CWE Content Team
MITRE
2022-06-07
4.8
2022-06-28

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

CWE Content Team
MITRE
2023-04-27
updated Relationships

CWE Content Team
MITRE
2023-06-29
updated Mapping_Notes

CWE Content Team
MITRE
2025-12-11
4.19
2025-12-11
updated Weakness_Ordinalities