In Git for Windows, the Windows port of Git, no localized messages are shipped with the installer. As a consequence, Git is expected not to localize messages at all, and skips the gettext initialization. However, due to a change in MINGW-packages, the gettext() functions implicit initialization no longer uses the runtime prefix but uses the hard-coded path C:mingw64sharelocale to look for localized messages. And since any authenticated user has the permission to create folders in C: (and since C:mingw64 does not typically exist), it is possible for low-privilege users to place fake messages in that location where git.exe will pick them up in version 2.40.1.
This vulnerability is relatively hard to exploit and requires social engineering. For example, a legitimate message at the end of a clone could be maliciously modified to ask the user to direct their web browser to a malicious website, and the user might think that the message comes from Git and is legitimate. It does require local write access by the attacker, though, which makes this attack vector less likely. Version 2.40.1 contains a patch for this issue. Some workarounds are available. Do not work on a Windows machine with shared accounts, or alternatively create a C:mingw64 folder and leave it empty. Users who have administrative rights may remove the permission to create folders in C:.
The product uses a function that accepts a format string as an argument, but the format string originates from an external source.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Git_for_windows | Git_for_windows_project | * | * |
When an attacker can modify an externally-controlled format string, this can lead to buffer overflows, denial of service, or data representation problems. It should be noted that in some circumstances, such as internationalization, the set of format strings is externally controlled by design. If the source of these format strings is trusted (e.g. only contained in library files that are only modifiable by the system administrator), then the external control might not itself pose a vulnerability.