CVE-2026-8106: Reflected HTML injection vulnerability in GitHub Enterprise Server Management Console login page allowed credential theft

Severity: medium (CVSS 6.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-05-07 · updated 2026-10-26
Weakness: CWE-79

Description

A reflected HTML injection vulnerability was identified in the GitHub Enterprise Server Management Console login page that could allow credential theft. The redirect_to query parameter on the /setup/unlock endpoint was reflected into an HTML attribute without proper sanitization, enabling an attacker to inject a form element that could capture administrator credentials. Exploitation required an administrator to click a crafted link and enter their credentials. This vulnerability affected GitHub Enterprise Server versions 3.19.1 through 3.19.5 and 3.20.0 through 3.20.1, and was fixed in versions 3.19.6 and 3.20.2. This vulnerability was reported via the GitHub Bug Bounty program.

Affected products

GitHub Enterprise Server: from 3.19.1 before 3.19.6; from 3.20.0 before 3.20.2 — fixed in 3.19.6, 3.20.2

How to fix

Upgrade to a fixed version: GitHub Enterprise Server 3.19.6, 3.20.2. Check the vendor advisory for mitigations.

References

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