Potential time of check time of use vulnerability (tmpnam/tempnam)

Description

There exists a possible race condition in between the time that `tempnam` or `tmpnam` returns a pathname, and the time that the program opens it, another program might create that pathname using `open`, or create it as a symbolic link. Consider using the `mkstemp` function instead, but be aware it also contains possible risks. Ensure the process has called the `umask` function with restricted permissions prior to calling `mkstemp` and validate the permissions prior to using the file descriptor.

Examples

Insecure Code

char *filename = tempnam(NULL, NULL);

Secure Code

int fd = mkstemp(template); if (fd == -1) { /* handle error */ }

Remediation

Use `mkstemp` instead of `tempnam` or `tmpnam`, and ensure the process has called the `umask` function with restricted permissions prior to calling `mkstemp`.

Rule Details

Field	Value
ID	CODE-0620
Category	InsecureConfig
Severity	MEDIUM
CWE	CWE-377
Confidence	HIGH
Impact	MEDIUM
Likelihood	MEDIUM
Exploitability	MODERATE
Tags	tempnam, tmpnam, mkstemp, race condition
OWASP	A5:2017-Broken Access Control, A01:2021-Broken Access Control

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