git-ecosystem/git-credential-manager

Git is a fast, scalable, distributed revision control system with an unusually rich command set that provides both high-level operations and full access to internals. Git defines a line-based protocol that is used to exchange information between Git and Git credential helpers. Some ecosystems (most notably, .NET and node.js) interpret single Carriage Return characters as newlines, which renders the protections against CVE-2020-5260 incomplete for credential helpers that treat Carriage Returns in this way. This issue has been addressed in commit `b01b9b8` which is included in release versions v2.48.1, v2.47.2, v2.46.3, v2.45.3, v2.44.3, v2.43.6, v2.42.4, v2.41.3, and v2.40.4. Users are advised to upgrade. Users unable to upgrade should avoid cloning from untrusted URLs, especially recursive clones.

Git Credential Manager (GCM) is a secure Git credential helper built on .NET that runs on Windows, macOS, and Linux. The Git credential protocol is text-based over standard input/output, and consists of a series of lines of key-value pairs in the format `key=value`. Git's documentation restricts the use of the NUL (`\0`) character and newlines to form part of the keys or values. When Git reads from standard input, it considers both LF and CRLF as newline characters for the credential protocol by virtue of calling `strbuf_getline` that calls to `strbuf_getdelim_strip_crlf`. Git also validates that a newline is not present in the value by checking for the presence of the line-feed character (LF, `\n`), and errors if this is the case. This captures both LF and CRLF-type newlines. Git Credential Manager uses the .NET standard library `StreamReader` class to read the standard input stream line-by-line and parse the `key=value` credential protocol format. The implementation of the `ReadLineAsync` method considers LF, CRLF, and CR as valid line endings. This is means that .NET considers a single CR as a valid newline character, whereas Git does not. This mismatch of newline treatment between Git and GCM means that an attacker can craft a malicious remote URL. When a user clones or otherwise interacts with a malicious repository that requires authentication, the attacker can capture credentials for another Git remote. The attack is also heightened when cloning from repositories with submodules when using the `--recursive` clone option as the user is not able to inspect the submodule remote URLs beforehand. This issue has been patched in version 2.6.1 and all users are advised to upgrade. Users unable to upgrade should only interact with trusted remote repositories, and not clone with `--recursive` to allow inspection of any submodule URLs before cloning those submodules.

Git Credential Manager (GCM) is a secure Git credential helper. Prior to 2.5.0, the Debian package does not set root ownership on installed files. This allows user 1001 on a multi-user system can replace binary and gain other users' privileges. This vulnerability is fixed in 2.5.0.

Git Credential Manager Core (GCM Core) is a secure Git credential helper built on .NET Core that runs on Windows and macOS. In Git Credential Manager Core before version 2.0.289, when recursively cloning a Git repository on Windows with submodules, Git will first clone the top-level repository and then recursively clone all submodules by starting new Git processes from the top-level working directory. If a malicious git.exe executable is present in the top-level repository then this binary will be started by Git Credential Manager Core when attempting to read configuration, and not git.exe as found on the %PATH%. This only affects GCM Core on Windows, not macOS or Linux-based distributions. GCM Core version 2.0.289 contains the fix for this vulnerability, and is available from the project's GitHub releases page. GCM Core 2.0.289 is also bundled in the latest Git for Windows release; version 2.29.2(3). As a workaround, users should avoid recursively cloning untrusted repositories with the --recurse-submodules option.