CVE-2021-21300

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.

How to fix CVE-2021-21300

To remediate CVE-2021-21300, upgrade the affected package to a fixed version below.

• —upgrade to 2.22.5-r0 or later
• —upgrade to 1:2.30.2-1 or later
• —upgrade to 1:2.20.1-2+deb10u4 or later

Is CVE-2021-21300 being exploited?

Likely — EPSS is 58.3%, placing CVE-2021-21300 in the top tier of vulnerabilities by exploitation probability. Prioritise patching.

Affected packages (3)

• from 0, < 2.22.5-r0
• from 0, < 1:2.30.2-1
• from 0, < 1:2.20.1-2+deb10u4

CVSS scores

References (2)

• ADVISORYsecurity.alpinelinux.org/vuln/CVE-2021-21300
• ADVISORYsecurity-tracker.debian.org/tracker/CVE-2021-21300