CVE-2026-18730: A server-side request forgery (SSRF) vulnerability was identified in GitHub Enterprise Server that allowed an

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HIGH 7.4REMOTEUPGRADE

CVE-2026-18730 is a high-severity flaw (CVSS 7.4) 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 GitHub Enterprise Server that allowed an unauthenticated attacker to cause the Manage API to send crafted outbound requests to an attacker-controlled host. An unauthenticated endpoint parsed an attacker-supplied cluster configuration and issued gateway-to-agent requests whose HMAC authenticated only a timestamp, not the request path or body. An attacker positioned to intercept t

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.4 (High)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 59%)
CISA exploited list	No
Weakness	CWE-918
Published	2026-09-01
Last modified	2026-09-22

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

Last updated 2026-09-22 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-09-01 22:17 UTCPublished CVE record published
2026-09-22 21:17 UTCUpdated Record last modified

github enterprise server UPGRADE

Affected: < 3.17.19 · >= 3.18.0 and < 3.18.13 · >= 3.19.0 and < 3.19.10 · >= 3.20.0 and < 3.20.6 · >= 3.21.0 and < 3.21.4

Fixed in: 3.17.19, 3.18.13, 3.19.10, 3.20.6, 3.21.4

Safe to downgrade to: a release before 3.18.0

1. Check installed version

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

2. UPGRADE to 3.17.19 (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 3.18.0 (Debian / Ubuntu)

apt-cache madison enterprise-server sudo apt install enterprise-server=<VERSION_BEFORE_3.18.0> 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_3.18.0> 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-2026-18730?

enterprise server: upgrade to 3.17.19, 3.18.13, 3.19.10, 3.20.6, 3.21.4. Exact commands for each OS are on this page.

Is CVE-2026-18730 being exploited?

CVE-2026-18730 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-2026-18730 affect?

CVE-2026-18730 affects enterprise server. Severity is high (CVSS 7.4). A server-side request forgery (SSRF) vulnerability was identified in GitHub Enterprise Server that allowed an unauthenticated attacker to cause the Manage API to send crafted outbound requests to an attacker-controlled host. An unauthentica

How urgent is CVE-2026-18730?

Priority 41/100. High severity; Remotely exploitable, no login, no user action

Software pages

GitHub vulnerabilities

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References

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