Home→Vulnerabilities→CVE-2026-8034
Critical Risk Disclosed

CVE-2026-8034

A server-side request forgery (SSRF) vulnerability was identified in the GitHub Enterprise Server notebook viewer that allowed an attacker to access internal services by exploiting URL parser confusion between the validation layer and the HTTP request library. The hostname validation used a different URL parser than the request library, enabling a crafted URL to pass validation while directing the request to an unintended host. Exploitation required network access to the GitHub Enterprise Server instance. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.21 and was fixed in versions 3.16.18, 3.17.15, 3.18.9, 3.19.6, and 3.20.2. This vulnerability was reported via the GitHub Bug Bounty program.

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Exploitation Probability (EPSS)

Low Priority
0.06%

The Exploit Prediction Scoring System (EPSS) uses machine learning to estimate the probability that a vulnerability will be exploited in the wild within the next 30 days.

0% (Theoretical)100% (Certainty)

7-Day Exploitation Trend

Vulnerability Timeline

2 events
May 7, 2026
Vulnerability Disclosed
Published to component-level vulnerability database.
May 11, 2026
Last Updated
Record updated with new analysis or tags.

Threat Actor Attribution

PREMIUM INTEL
Associated Groups:Lazarus Group, APT28
Ransomware Campaigns:LockBit 3.0, BlackCat
IoCs (Indicators):14 IPs, 3 Hashes

Remediation & Mitigation

SOLUTION

Official patches and mitigation steps are available for this vulnerability.

# Update Command
apt-get update && apt-get upgrade -y specific-package
# Verify installation
dpkg -l | grep package-name

Affected Products

1 Total
github/enterprise_serverAll Versions

References

https://docs.github.com/en/enterprise-server@3.16/admin/release-notes#3.16.18GitHub
Release NotesVendor Advisory
https://docs.github.com/en/enterprise-server@3.17/admin/release-notes#3.17.15GitHub
Release NotesVendor Advisory
https://docs.github.com/en/enterprise-server@3.18/admin/release-notes#3.18.9GitHub
Release NotesVendor Advisory
https://docs.github.com/en/enterprise-server@3.19/admin/release-notes#3.19.6GitHub
Release NotesVendor Advisory

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Vulnerability Details

CVSS Base Score
9.8/ 10
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published Date
May 7, 2026
Last Modified
May 11, 2026
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