CVE-2026-8034: A server-side request forgery (SSRF) vulnerability was identified in the GitHub Enterprise Server notebook vie

This month

CRITICAL 9.8REMOTEUPGRADE

CVE-2026-8034 is a critical-severity flaw (CVSS 9.8) affecting enterprise server. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 requi

Why this priority

Critical severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 56%)
CISA exploited list	No
Weakness	CWE-436, CWE-918
Published	2026-05-07
Last modified	2026-10-26

Publisher (CNA): GitHub, Inc. (Products Only) · Vendor: github

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-05-07 22:16 UTCPublished CVE record published
2026-10-26 20:10 UTCUpdated Record last modified

github enterprise server UPGRADE

Affected: < 3.16.18 · >= 3.17.0 and < 3.17.15 · >= 3.18.0 and < 3.18.9 · >= 3.19.0 and < 3.19.6 · >= 3.20.0 and < 3.20.2

Fixed in: 3.16.18, 3.17.15, 3.18.9, 3.19.6, 3.20.2

Safe to downgrade to: a release before 3.17.0

1. Check installed version

apt-cache policy enterprise-server || rpm -q enterprise-server || enterprise-server --version

2. UPGRADE to 3.16.18 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade enterprise-server

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade enterprise-server

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 3.17.0 (Debian / Ubuntu)

apt-cache madison enterprise-server sudo apt install enterprise-server=<VERSION_BEFORE_3.17.0> sudo apt-mark hold enterprise-server

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list enterprise-server sudo dnf downgrade enterprise-server-<VERSION_BEFORE_3.17.0> sudo dnf versionlock add enterprise-server

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-8034?

enterprise server: upgrade to 3.16.18, 3.17.15, 3.18.9, 3.19.6, 3.20.2. Exact commands for each OS are on this page.

Is CVE-2026-8034 being exploited?

CVE-2026-8034 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-8034 affect?

CVE-2026-8034 affects enterprise server. Severity is critical (CVSS 9.8). 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 H

How urgent is CVE-2026-8034?

Priority 50/100. Critical severity; Remotely exploitable, no login, no user action

Software pages

GitHub vulnerabilities

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References

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