CVE-2026-4296

What it is

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.

At a glance

Exploitability

Can be exploited over the network with a low-privilege account, but needs a user to act. High risk of data exposure, data tampering, service disruption.

Exploit odds

0.4% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-04-21 23:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-10-26 22:10 UTC Last updatedMost recent change to the record

Details

Published

2026-04-21 23:16 UTC

Last modified

2026-10-26 22:10 UTC

Exploit probability

0.4% · EPSS, next 30 days

Weakness

CWE-185

Record status

Analyzed

Affected

• GitHub Enterprise Server < 3.14.26
• GitHub Enterprise Server < 3.15.21
• GitHub Enterprise Server < 3.16.17
• GitHub Enterprise Server < 3.17.14
• GitHub Enterprise Server < 3.18.8
• GitHub Enterprise Server < 3.19.5
• GitHub Enterprise Server 3.20.0

Attack profile CVSS 4.0 · 7.5

Attack vector

Network

Complexity

Low

Attack requirements

Present

Privileges needed

Low

User interaction

Passive

Confidentiality

High

Integrity

High

Availability

High