CVE-2021-21300 Information

Description

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.

CVSS Vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

Reference

https://github.com/git/git/commit/684dd4c2b414bcf648505e74498a608f28de4592 https://git-scm.com/docs/gitattributes#_filter https://github.com/git/git/security/advisories/GHSA-8prw-h3cq-mghm https://lore.kernel.org/git/xmqqim6019yd.fsf@gitster.c.googlers.com/ https://git-scm.com/docs/git-config#Documentation/git-config.txt-coresymlinks http://www.openwall.com/lists/oss-security/2021/03/09/3 https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/LCLJJLKKMS5WRFO6C475AOUZTWQLIARX/ https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/LMXX2POK5X576BSDWSXGU7EIK6I72ERU/ https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/BBPNGLQSYJHLZZ37BO42YY6S5OTIF4L4/ https://support.apple.com/kb/HT212320 http://seclists.org/fulldisclosure/2021/Apr/60 https://security.gentoo.org/glsa/202104-01 http://packetstormsecurity.com/files/163978/Git-LFS-Clone-Command-Execution.html

Attack Complexity

HIGH

Privileges Required

NONE

User Interaction Required

NONE

Scope

REQUIRED

Confidentiality Impact

UNCHANGED

Integrity Impact

HIGH

Availability Impact

HIGH

Base Score

HIGH

Base Severity

7.5