CVE-2026-4296

HIGH
MEDIUM Priority: 0.03 BB Relevance: 55/100
Published: 2026-04-21 Modified: 2026-10-26 First seen: 2026-10-29 Status: active

Attack Surface

Network Low Complexity Conf. Impact Integ. Impact

CVSS Vector Breakdown

AV: Network
AC: Low
PR: Low
UI: Passive
S: X
AT: Present
VC: High
VI: High
VA: High

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.

Weakness Classification (1)

Affected Software (7)

VendorProductVersion
github enterprise_server < 3.14.26
github enterprise_server 3.15.0 – 3.15.21
github enterprise_server 3.16.0 – 3.16.17
github enterprise_server 3.17.0 – 3.17.14
github enterprise_server 3.18.0 – 3.18.8
github enterprise_server 3.19.0 – 3.19.5
github enterprise_server 3.20.0

Bug Bounty Relevance

55 / 100
✓ Network accessible
✓ Low complexity

CVSS Score

7.5 / 10.0 v4.0
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS — Exploitation Probability

0.43%
Raw Score 0.004260
Percentile 36.8%
Date 2026-10-29

EPSS Trend

2026-10-29
0.00426
2026-10-28
0.00426

Intelligence Sources

nvd ref →