GitHubApplication
CVE-2020-10518
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedA remote code execution vulnerability was identified in GitHub Enterprise Server that could be exploited when building a GitHub Pages site. User-controlled configuration of the underlying parsers used by GitHub Pages were not sufficiently restricted and made it possible to execute commands on the GitHub Enterprise Server instance. To exploit this vulnerability, an attacker would need permission to create and build a GitHub Pages site on the GitHub Enterprise Server instance. This vulnerability affected all versions of GitHub Enterprise Server prior to 2.22 and was fixed in 2.21.6, 2.20.15, and 2.19.21. The underlying issues contributing to this vulnerability were identified both internally and through the GitHub Security Bug Bounty program.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceA remote code execution vulnerability in GitHub Enterprise Server's GitHub Pages feature allowed attackers with permissions to create/build Pages sites to execute commands on the server. The root cause was insufficient restrictions on user-controlled configuration of parsers used by GitHub Pages.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
GitHubApplication
< 2.19.21>= 2.20.0, < 2.20.15>= 2.21.0, < 2.21.6CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify GitHub Enterprise Server installationRun 'ghe-version' command or check the admin console for the product name. This vulnerability only affects GitHub Enterprise Server, not GitHub.com (github.com).Affected if The product is GitHub Enterprise Server
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Check installed GitHub Enterprise Server versionRun 'ghe-version' from the command line or view the version in the admin console under 'About' or 'Settings'. Compare the version number to the affected ranges: < 2.19.21, >= 2.20.0 and < 2.20.15, or >= 2.21.0 and < 2.21.6.Affected if The installed version falls within any of the affected version ranges (pre-2.19.21, 2.20.x before 2.20.15, or 2.21.x before 2.21.6)
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Verify GitHub Pages feature is enabledNavigate to the admin console, go to 'Pages' settings, or use the API endpoint '/enterprise/settings/pages' to confirm whether GitHub Pages is enabled for the instance.Affected if GitHub Pages is enabled for the enterprise instance
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Check user permissions for Pages creationReview organization and repository settings to determine if non-admin users have the ability to create or build GitHub Pages sites. Check site-wide enterprise settings under 'GitHub Pages' in the admin console.Affected if Regular users (non-administrators) have permissions to create or build GitHub Pages sites
You are affected if you are running a vulnerable GitHub Enterprise Server version (before 2.19.21, 2.20.x before 2.20.15, or 2.21.x before 2.21.6) AND have GitHub Pages enabled with non-admin users able to create or build Pages sites.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor data2.19.212.20.152.21.6
Upgrade GitHub Enterprise Server to version 2.21.6, 2.20.15, 2.19.21 or later to remediate this vulnerability.
Fix this in GitHub
Scoped from the published advisory
- Consultation4.0 h
- Implementation8.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,120.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-10518 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2020-10518 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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