CVE-2020-5260

Affected versions of Git have a vulnerability whereby Git can be tricked
into sending private credentials to a host controlled by an attacker. Git
uses external “credential helper” programs to store and retrieve passwords
or other credentials from secure storage provided by the operating system.
Specially-crafted URLs that contain an encoded newline can inject
unintended values into the credential helper protocol stream, causing the
credential helper to retrieve the password for one server (e.g.,
good.example.com) for an HTTP request being made to another server (e.g.,
evil.example.com), resulting in credentials for the former being sent to
the latter. There are no restrictions on the relationship between the two,
meaning that an attacker can craft a URL that will present stored
credentials for any host to a host of their choosing. The vulnerability can
be triggered by feeding a malicious URL to git clone. However, the affected
URLs look rather suspicious; the likely vector would be through systems
which automatically clone URLs not visible to the user, such as Git
submodules, or package systems built around Git. The problem has been
patched in the versions published on April 14th, 2020, going back to
v2.17.x. Anyone wishing to backport the change further can do so by
applying commit 9a6bbee (the full release includes extra checks for git
fsck, but that commit is sufficient to protect clients against the
vulnerability). The patched versions are: 2.17.4, 2.18.3, 2.19.4, 2.20.3,
2.21.2, 2.22.3, 2.23.2, 2.24.2, 2.25.3, 2.26.1.