Security vulnerability in Git for Cygwin

[Adam Dinwoodie]

Hi folks,

Version 2.31.1-2 of Git has been uploaded and should be coming soon to
a mirror near you.

This update addresses CVE-2021-29468, which would cause Git to
overwrite arbitrary files with attacker-controlled contents when
checking out content from a malicious repository, and in particular
would allow an attacker to overwrite Git hooks to execute arbitrary
code.

This vulnerability is present on all Cygwin Git versions prior to
v2.31.1-2. Until you have that release, the best mitigation is to not
clone or check out from any untrusted Git repositories.

There is a small amount of additional information in the GitHub
Security Advisory at
https://github.com/me-and/Cygwin-Git/security/advisories/GHSA-rmp3-wq55-f557

If you compile Git on Cygwin yourself, there is currently no upstream
patch that addresses the vulnerability. Until there is, I would
recommend applying the preliminary patch at
https://github.com/me-and/Cygwin-Git/blob/main/check-backslash-safety.patch

I'd like to thank RyotaK (https://github.com/Ry0taK /
https://twitter.com/ryotkak) for finding and responsibly disclosing
this vulnerability, and Johannes Schindelin for helping manage the
response.

Kind regards,

Adam