high
8
CWE
59
Advisory Published
Updated

CVE-2021-21300: malicious repositories can execute remote code while cloning

First published: Tue Mar 09 2021(Updated: )

Git is an open-source distributed revision control system. In affected versions of Git a specially crafted repository that contains symbolic links as well as files using a clean/smudge filter such as Git LFS, may cause just-checked out script to be executed while cloning onto a case-insensitive file system such as NTFS, HFS+ or APFS (i.e. the default file systems on Windows and macOS). Note that clean/smudge filters have to be configured for that. Git for Windows configures Git LFS by default, and is therefore vulnerable. The problem has been patched in the versions published on Tuesday, March 9th, 2021. As a workaound, if symbolic link support is disabled in Git (e.g. via `git config --global core.symlinks false`), the described attack won't work. Likewise, if no clean/smudge filters such as Git LFS are configured globally (i.e. _before_ cloning), the attack is foiled. As always, it is best to avoid cloning repositories from untrusted sources. The earliest impacted version is 2.14.2. The fix versions are: 2.30.1, 2.29.3, 2.28.1, 2.27.1, 2.26.3, 2.25.5, 2.24.4, 2.23.4, 2.22.5, 2.21.4, 2.20.5, 2.19.6, 2.18.5, 2.17.62.17.6.

Credit: an anonymous researcher security-advisories@github.com

Affected SoftwareAffected VersionHow to fix
Apple Xcode<12.5
12.5
Git-scm Git<=2.14.2
Git-scm Git>=2.17.0<2.17.6
Git-scm Git>=2.18.0<2.18.5
Git-scm Git>=2.19.0<2.19.6
Git-scm Git>=2.20.0<2.20.5
Git-scm Git>=2.21.0<2.21.4
Git-scm Git>=2.22.0<2.22.5
Git-scm Git>=2.24.0<2.24.4
Git-scm Git>=2.25.0<2.25.5
Git-scm Git>=2.26.0<2.26.3
Git-scm Git>=2.29.0<2.29.3
Git-scm Git>=2.30.0<2.30.2
Git-scm Git=2.27.0
Git-scm Git=2.28.0
Fedoraproject Fedora=32
Fedoraproject Fedora=33
Fedoraproject Fedora=34
Apple Xcode<12.5
Apple macOS>=11.0
Debian Debian Linux=10.0

Remedy

https://github.com/git/git/commit/684dd4c2b414bcf648505e74498a608f28de4592

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Reference Links

Parent vulnerabilities

(Appears in the following advisories)

Peer vulnerabilities

(Found alongside the following vulnerabilities)

Frequently Asked Questions

  • What is CVE-2021-21300?

    CVE-2021-21300 is a vulnerability in Git that allows a specially crafted repository to execute arbitrary code.

  • What is the severity of CVE-2021-21300?

    CVE-2021-21300 has a severity rating of 7.5 (high).

  • Which versions of Git are affected by CVE-2021-21300?

    Git versions up to and including 2.14.2, and versions between 2.17.0 and 2.26.3 are affected by CVE-2021-21300.

  • How can I fix CVE-2021-21300?

    To fix CVE-2021-21300, it is recommended to update Git to a version that is not affected by the vulnerability.

  • Where can I find more information about CVE-2021-21300?

    You can find more information about CVE-2021-21300 in the references provided: [link1](https://support.apple.com/en-us/HT212320), [link2](http://packetstormsecurity.com/files/163978/Git-LFS-Clone-Command-Execution.html), [link3](http://seclists.org/fulldisclosure/2021/Apr/60).

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