CVE-2021-21300

low

Published — · Modified —

💬 Discuss on Community ✚ Propose mitigation

CVSS v3

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CVSS v4 NEW

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not yet in upstream

VIR risk

3.5

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.

Predictions

Exploit likelihood

20%

Patch ETA

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Heuristic predictions, AS-IS, for prioritization only.

Mitigations

No mitigations published for this CVE yet.

The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.

✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here with source_tier=community-verified.

Exploits

Public proof-of-concept code below. AS-IS, for defenders and authorised testing only.

Metasploit modules

exploit_multi/http/git_lfs_clone_command_exec rank 600

Git LFS Clone Command Exec

Source fetch failed: fetch_error — view the original via the link above.

OS impact

SUSE Affected 1 release

Version	Status	Fixed in
—	Affected	—

Arch Fixed 1 release

Version	Status	Fixed in
—	Fixed	`2.30.2-1`

Debian Fixed 5 releases

Version	Status	Fixed in
trixie	Fixed	`1:2.30.2-1`
sid	Fixed	`1:2.30.2-1`
forky	Fixed	`1:2.30.2-1`
bullseye	Fixed	`1:2.30.2-1`
bookworm	Fixed	`1:2.30.2-1`

References

Community-verified mitigations for this CVE will appear above when contributors publish them.

Verify integrity in audit chain (admin only). AS-IS.