Cyber Resilience

CVE-2021-21300

HighPublic PoC

Published: 09 March 2021

Published
09 March 2021
Modified
21 November 2024
KEV Added
Patch
CVSS Score v3.1 8.0 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N
EPSS Score 0.5828 98.2th percentile
Risk Priority 51 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2021-21300 is a high-severity Link Following (CWE-59) vulnerability in Git-Scm Git. Its CVSS base score is 8.0 (High).

Operationally, ranked in the top 1.8% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

EU & UK References

Vulnerability details

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…

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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.

CWE(s)

Related Threats

No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.

Affected Assets

git-scm
git
2.27.0, 2.28.0 · ≤ 2.14.2 · 2.17.0 — 2.17.6 · 2.18.0 — 2.18.5
fedoraproject
fedora
32, 33, 34
apple
xcode
≤ 12.5
debian
debian linux
10.0

Mitigating Controls

No mitigating controls mapped yet. The per-CVE control annotator has not reached this CVE.

References