Vulnerability in Apple macOS
CVE-2021-21300
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.
EPSS: 0.886 (99.8th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 8.0 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N.
Affected products
- Apple Macos
- Apple Xcode
- Git — versions >= 2.14.2, < 2.17.62.17.6, >= 2.18.0, < 2.18.5, >= 2.19.0, < 2.19.6
- Git-scm Git — versions 2.27.0, 2.28.0
- Debian Debian_linux — versions 10.0
- Fedoraproject Fedora — versions 32, 33, 34
Weakness classification (CWE)
Public proof-of-concept exploits
References
- security-advisories@github.com (Third Party Advisory)
- security-advisories@github.com
- security-advisories@github.com (Vendor Advisory)
- security-advisories@github.com (Vendor Advisory)
- security-advisories@github.com (Patch, Third Party Advisory)
- security-advisories@github.com (mailing-list, Exploit, Mailing List, Third Party Advisory)
- security-advisories@github.com (vendor-advisory)
- security-advisories@github.com (vendor-advisory)
- security-advisories@github.com (vendor-advisory)
- security-advisories@github.com (Third Party Advisory)
Frequently asked questions
- What is CVE-2021-21300?
- CVE-2021-21300 is a high-severity vulnerability in Apple macOS, classified under Improper Link Resolution Before File Access. CVSS score: 8.0/10. Published 2021-03-09.
- How severe is CVE-2021-21300?
- High severity. CVSS v3 base score is 8.0 out of 10.
- Is CVE-2021-21300 known to be exploited?
- 60 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.