CVE-2021-21300

high

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.

References

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/[email protected]/

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/[email protected]/message/LCLJJLKKMS5WRFO6C475AOUZTWQLIARX/

https://lists.fedoraproject.org/archives/list/[email protected]/message/LMXX2POK5X576BSDWSXGU7EIK6I72ERU/

https://lists.fedoraproject.org/archives/list/[email protected]/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

Details

Source: MITRE

Published: 2021-03-09

Updated: 2021-09-23

Type: CWE-59

Risk Information

CVSS v2

Base Score: 5.1

Vector: AV:N/AC:H/Au:N/C:P/I:P/A:P

Impact Score: 6.4

Exploitability Score: 4.9

Severity: MEDIUM

CVSS v3

Base Score: 7.5

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

Impact Score: 5.9

Exploitability Score: 1.6

Severity: HIGH