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CVE-2021-21300

HIGHCVSS 7.5/10EPSS 88.64%

Last modified

CVE-2021-21300 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. 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. EPSS estimates a 88.64% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1
7.5/10

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

EPSS Probability
88.64%

99.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
Git-ScmGit<= 2.14.2
Git-ScmGit>= 2.17.0, < 2.17.6
Git-ScmGit>= 2.18.0, < 2.18.5
Git-ScmGit>= 2.19.0, < 2.19.6
Git-ScmGit>= 2.20.0, < 2.20.5
Git-ScmGit>= 2.21.0, < 2.21.4
Git-ScmGit>= 2.22.0, < 2.22.5
Git-ScmGit>= 2.23.0, < 2.23.4
Git-ScmGit>= 2.24.0, < 2.24.4
Git-ScmGit>= 2.25.0, < 2.25.5
Git-ScmGit>= 2.26.0, < 2.26.3
Git-ScmGit>= 2.29.0, < 2.29.3
Git-ScmGit>= 2.30.0, < 2.30.2
Git-ScmGit2.27.0
Git-ScmGit2.28.0
FedoraprojectFedora32
FedoraprojectFedora33
FedoraprojectFedora34
AppleXcode< 12.5
DebianDebian Linux10.0

References

Timeline

Published
Last Modified
Status
Modified

Frequently Asked Questions

What is 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.
How severe is CVE-2021-21300?
CVE-2021-21300 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 88.64% probability of exploitation in the next 30 days.
How do I fix CVE-2021-21300?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-21300?

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Source: NVD / NIST