CVE-2021-22861: Improper access control in GitHub Enterprise Server leading to unauthorized write access to forkable repositories
First published: Wed Mar 03 2021(Updated: )
An improper access control vulnerability was identified in GitHub Enterprise Server that allowed authenticated users of the instance to gain write access to unauthorized repositories via specifically crafted pull requests and REST API requests. An attacker would need to be able to fork the targeted repository, a setting that is disabled by default for organization owned private repositories. Branch protections such as required pull request reviews or status checks would prevent unauthorized commits from being merged without further review or validation. This vulnerability affected all versions of GitHub Enterprise Server since 2.4.21 and was fixed in versions 2.20.24, 2.21.15, 2.22.7 and 3.0.1. This vulnerability was reported via the GitHub Bug Bounty program.
Credit: product-cna@github.com
| Affected Software | Affected Version | How to fix |
|---|---|---|
| GitHub GitHub | >=2.4.21<2.20.24 | |
| GitHub GitHub | >=2.21.0<2.21.15 | |
| GitHub GitHub | >=2.22.0<2.22.7 | |
| GitHub GitHub | >=3.0.0<3.0.1 |
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Reference Links
- https://docs.github.com/en/enterprise-server@2.20/admin/release-notes#2.20.24
- https://docs.github.com/en/enterprise-server@2.21/admin/release-notes#2.21.15
- https://docs.github.com/en/enterprise-server@2.22/admin/release-notes#2.22.7
- https://docs.github.com/en/enterprise-server@3.0/admin/release-notes#3.0.1
- https://docs.github.com/en/enterprise-server%402.20/admin/release-notes#2.20.24
- https://docs.github.com/en/enterprise-server%402.21/admin/release-notes#2.21.15
- https://docs.github.com/en/enterprise-server%402.22/admin/release-notes#2.22.7
- https://docs.github.com/en/enterprise-server%403.0/admin/release-notes#3.0.1
Frequently Asked Questions
What is CVE-2021-22861?
CVE-2021-22861 is an improper access control vulnerability identified in GitHub Enterprise Server that allowed authenticated users to gain write access to unauthorized repositories.
How does CVE-2021-22861 affect GitHub Enterprise Server?
CVE-2021-22861 affects GitHub Enterprise Server versions between 2.4.21 and 2.20.24, 2.21.0 and 2.21.15, and 2.22.0 and 2.22.7.
What is the severity of CVE-2021-22861?
CVE-2021-22861 has a severity rating of 6.5 (medium).
How can an attacker exploit CVE-2021-22861?
An attacker can exploit CVE-2021-22861 by creating specifically crafted pull requests and REST API requests to gain write access to unauthorized repositories.
Are there any fixes or patches available for CVE-2021-22861?
Yes, GitHub has released patches for CVE-2021-22861. It is recommended to upgrade to the latest patched version of GitHub Enterprise Server.
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