dialog /tmp File Race Condition Vulnerability

dialog is a program available with distributions of the Linux Operating System. A problem exists which could allow a user to append to or overwrite files owned by another user.

Various programs such as debconf are dependent upon dialog. However, dialog creates lock files in the /tmp directory insecurely. A brute force attack involving creating numerous symbolic links in the /tmp filesystem makes it possible to truncate any linked file that is writable by the user executing dialog (be it directly, or through another program). It is possible for a user with malicious intent to exploit this vulnerability and truncate, corrupt, or overwrite sensitive files that privileged only to the user executing dialog.


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