CVE-2020-5260 malicious URLs may cause Git to present stored credentials to the wrong server

What is CVE-2020-5260?

CVE-2020-5260 is a critical vulnerability in Canonical Ubuntu Linux, published on 14 Apr 2020. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

Official description

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.

Weakness: CWE-522, CWE-20

Which versions are affected by CVE-2020-5260?

1 open source package ship an affected version, including git. It affects 6 products.

Products include Canonical Ubuntu Linux, Debian Debian Linux, Fedoraproject Fedora, Git-Scm Git, Git Git, Opensuse Leap.

How do I fix CVE-2020-5260?

Upgrade git to a fixed version for your release line: 2.17.4 or 2.22.3.

Is CVE-2020-5260 being exploited?

There is no known exploitation of CVE-2020-5260 in the wild and no public exploit code.

Public exploit code: 3 proofs of concept on GitHub.

Other vulnerabilities in Canonical Ubuntu Linux

• CVE-2020-11651 SaltStack Salt Authentication Bypass Exploited Critical 9.8
• CVE-2020-7247 OpenSMTPD Remote Code Execution Exploited Critical 9.8
• CVE-2019-16928 Exim Out-of-bounds Write Exploited Critical 9.8
• CVE-2018-6789 Exim Buffer Overflow Exploited Critical 9.8
• CVE-2015-2590 Oracle Java SE and Java SE Embedded Remote Code Execution Exploited Critical 9.8

All Canonical Ubuntu Linux vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as ALPINE-CVE-2020-5260, BIT-git-2020-5260, CLEANSTART-2025-KZ78895, DEBIAN-CVE-2020-5260, DLA-2177-1, DSA-4657-1 and 11 more.