Enterprise ServerApplication · GitHub
CVE-2026-4296
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 · uneditedAn incorrect regular expression vulnerability was identified in GitHub Enterprise Server that allowed an attacker to bypass OAuth redirect URI validation. An attacker with knowledge of a first-party OAuth application's registered callback URL could craft a malicious authorization link that, when clicked by a victim, would redirect the OAuth authorization code to an attacker-controlled domain. This could allow the attacker to gain unauthorized access to the victim's account with the scopes granted to the OAuth application. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.21 and was fixed in versions 3.20.1, 3.19.5, 3.18.8, 3.17.14, 3.16.17, 3.15.21, 3.14.26. This vulnerability was reported via the GitHub 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 confidenceGitHub Enterprise Server contains an incorrect regular expression in OAuth redirect URI validation that allows attackers to bypass the whitelist and redirect authorization codes to attacker-controlled domains by crafting malicious authorization links.
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
Enterprise ServerApplication
< 3.14.26>= 3.15.0, < 3.15.21>= 3.16.0, < 3.16.17>= 3.17.0, < 3.17.14>= 3.18.0, < 3.18.8>= 3.19.0, < 3.19.5= 3.20.0CVSS 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
- None
- User interaction
- Required
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/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 versionRun 'ghe-version' from the management shell or check the admin console dashboard for the current version numberAffected if The installed version falls within any of these ranges: < 3.14.26, >= 3.15.0 and < 3.15.21, >= 3.16.0 and < 3.16.17, >= 3.17.0 and < 3.17.14, >= 3.18.0 and < 3.18.8, >= 3.19.0 and < 3.19.5, or exactly 3.20.0
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Verify OAuth application configurationNavigate to Site Admin > OAuth applications or use the API endpoint /api/v3/applications to list all registered OAuth apps and their redirect URIsAffected if OAuth applications are enabled and configured with redirect URIs
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Review OAuth redirect URIs for suspicious patternsExamine each OAuth application's Authorization callback URL field for domains that are not owned by your organization, unusually long URLs, or domains containing typical attacker patterns (for example, look for redirects to external domains not in your allowlist)Affected if Any OAuth application has a redirect URI pointing to an unexpected or external domain, or exhibits regex-bypass characteristics like nested subdomains or unusual URL structures
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Check audit logs for OAuth authorization anomaliesIn the admin console, go to Auditing > Search and filter for events like 'oauth_authorization' or 'oauth_access_token', paying attention to redirects that lead to unfamiliar domainsAffected if Audit logs show OAuth authorization codes being sent to domains not explicitly allowed in your OAuth configuration
A user is affected if they run a vulnerable GitHub Enterprise Server version AND have OAuth applications configured, with the vulnerability exploitable through maliciously crafted redirect URIs in authorization links.
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.
dbcve · scoped3.14.263.15.213.16.17
Upgrade GitHub Enterprise Server to one of the fixed versions (3.20.1, 3.19.5, 3.18.8, 3.17.14, 3.16.17, 3.15.21, 3.14.26 or later). Review OAuth application registrations for suspicious callback URLs.
3.14.26, 3.15.21, 3.16.17, 3.17.14, or later (3.18.x, 3.19.x, 3.20.x, 3.21+)
- 1. Identify the current GitHub Enterprise Server version by navigating to the admin console or running: ghe-version
- 2. Based on current version, determine the minimum fixed release needed: if < 3.14.26, upgrade to 3.14.26 or later; if >= 3.15.0 and < 3.15.21, upgrade to 3.15.21 or later; if >= 3.16.0 and < 3.16.17, upgrade to 3.16.17 or later; if >= 3.17.0 and < 3.17.14, upgrade to 3.17.14 or later
- 3. Review GitHub Enterprise Server upgrade prerequisites and backup procedures at docs.github.com
- 4. Perform the upgrade following the standard GitHub Enterprise Server upgrade process
- 5. After upgrade, verify the OAuth application redirect URI validation is working correctly
- 6. Audit existing OAuth applications to ensure redirect URIs are correctly configured
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Enterprise Server
Scoped from the published advisory
- Consultation4.0 h
- Implementation12.0 h
- Testing6.0 h
- Review / QA3.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $7,040.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-4296 — 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-2026-4296 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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- Version or environment caveats, and links to real fixes
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