The product creates a temporary file in a directory whose permissions allow unintended actors to determine the file's existence or otherwise access that file.
On some operating systems, the fact that the temporary file exists may be apparent to any user with sufficient privileges to access that directory. Since the file is visible, the application that is using the temporary file could be known. If one has access to list the processes on the system, the attacker has gained information about what the user is doing at that time. By correlating this with the applications the user is running, an attacker could potentially discover what a user's actions are. From this, higher levels of security could be breached.

Primary

Implementation

Low

Confidentiality
Read Application Data
Since the file is visible and the application which is using the temp file could be known, the attacker has gained information about what the user is doing at that time.

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

Requirements
Many contemporary languages have functions which properly handle this condition. Older C temp file functions are especially susceptible.

Implementation
Try to store sensitive tempfiles in a directory which is not world readable -- i.e., per-user directories.

Implementation
Avoid using vulnerable temp file functions.

In the following code examples a temporary file is created and written to. After using the temporary file, the file is closed and deleted from the file system.

FILE *stream;if( (stream = tmpfile()) == NULL ) {

perror("Could not open new temporary file\n");return (-1);
}
// write data to tmp file
...// remove tmp filermtmp();

However, within this C/C++ code the method tmpfile() is used to create and open the temp file. The tmpfile() method works the same way as the fopen() method would with read/write permission, allowing attackers to read potentially sensitive information contained in the temp file or modify the contents of the file.

try {File temp = File.createTempFile("pattern", ".suffix");temp.deleteOnExit();BufferedWriter out = new BufferedWriter(new FileWriter(temp));out.write("aString");out.close();}catch (IOException e) {}

Similarly, the createTempFile() method used in the Java code creates a temp file that may be readable and writable to all users.
Additionally both methods used above place the file into a default directory. On UNIX systems the default directory is usually "/tmp" or "/var/tmp" and on Windows systems the default directory is usually "C:\\Windows\\Temp", which may be easily accessible to attackers, possibly enabling them to read and modify the contents of the temp file.

CVE-2022-27818
A hotkey daemon written in Rust creates a domain socket file underneath /tmp, which is accessible by any user.
https://www.cve.org/CVERecord?id=CVE-2022-27818

CVE-2021-21290
A Java-based application for a rapid-development framework uses File.createTempFile() to create a random temporary file with insecure default permissions.
https://www.cve.org/CVERecord?id=CVE-2021-21290

Guessed or visible temporary file

FIO15-C
Ensure that file operations are performed in a secure directory

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.

CLASP
2006-07-19
Draft 3
2006-07-19

Eric Dalci
Cigital
2008-07-01
updated Time_of_Introduction

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

CWE Content Team
MITRE
2008-11-24
updated Relationships, Taxonomy_Mappings

CWE Content Team
MITRE
2009-05-27
updated Description, Name

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

CWE Content Team
MITRE
2011-06-01
updated Common_Consequences

CWE Content Team
MITRE
2011-09-13
updated Relationships, Taxonomy_Mappings

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

CWE Content Team
MITRE
2012-10-30
updated Demonstrative_Examples

CWE Content Team
MITRE
2014-07-30
updated Relationships

CWE Content Team
MITRE
2017-11-08
updated Applicable_Platforms, Demonstrative_Examples, Taxonomy_Mappings

CWE Content Team
MITRE
2019-06-20
updated Type

CWE Content Team
MITRE
2020-02-24
updated Name, References, Relationships, Type

CWE Content Team
MITRE
2021-03-15
updated Demonstrative_Examples

CWE Content Team
MITRE
2023-01-31
updated Description

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

CWE Content Team
MITRE
2023-06-29
updated Mapping_Notes

CWE Content Team
MITRE
2023-10-26
updated Observed_Examples

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

Guessed or Visible Temporary File
Creation of Temporary File in Directory with Insecure Permissions
Creation of Temporary File in Directory with Incorrect Permissions