CVE-2026-4296

Vulnerability Description

An 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.

CVSS Score

Affected Products

Related Weaknesses (CWE)

References

• https://docs.github.com/en/[email protected]/admin/release-notes#3.14.26Release NotesVendor Advisory
• https://docs.github.com/en/[email protected]/admin/release-notes#3.15.21Release NotesVendor Advisory
• https://docs.github.com/en/[email protected]/admin/release-notes#3.16.17Release NotesVendor Advisory
• https://docs.github.com/en/[email protected]/admin/release-notes#3.17.14Release NotesVendor Advisory
• https://docs.github.com/en/[email protected]/admin/release-notes#3.18.8Release NotesVendor Advisory
• https://docs.github.com/en/[email protected]/admin/release-notes#3.19.5Release NotesVendor Advisory
• https://docs.github.com/en/[email protected]/admin/release-notes#3.20.1Release NotesVendor Advisory