---
id: CVE-2026-18730
title: >-
  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
summary: >-
  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
  unauthent…
severity: high
cvss: 7.4
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N'
cwe:
  - CWE-918
vendor: github
product: enterprise_server
affected:
  - enterprise_server < 3.17.19
  - 'enterprise_server >= 3.18.0, < 3.18.13'
  - 'enterprise_server >= 3.19.0, < 3.19.10'
  - 'enterprise_server >= 3.20.0, < 3.20.6'
  - 'enterprise_server >= 3.21.0, < 3.21.4'
patched:
  - enterprise_server 3.21.4
published: '2026-09-01'
updated: '2026-09-22'
sourceUpdated: '2026-09-22T21:17:30.087'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-18730'
references:
  - url: >-
      https://docs.github.com/en/enterprise-server@3.17/admin/release-notes#3.17.21
    label: product-cna@github.com
  - url: >-
      https://docs.github.com/en/enterprise-server@3.18/admin/release-notes#3.18.15
    label: product-cna@github.com
  - url: >-
      https://docs.github.com/en/enterprise-server@3.19/admin/release-notes#3.19.12
    label: product-cna@github.com
  - url: >-
      https://docs.github.com/en/enterprise-server@3.20/admin/release-notes#3.20.8
    label: product-cna@github.com
  - url: >-
      https://docs.github.com/en/enterprise-server@3.21/admin/release-notes#3.21.6
    label: product-cna@github.com
  - url: >-
      https://docs.github.com/en/enterprise-server@3.17/admin/release-notes#3.17.19
    label: product-cna@github.com
  - url: >-
      https://docs.github.com/en/enterprise-server@3.18/admin/release-notes#3.18.13
    label: product-cna@github.com
  - url: >-
      https://docs.github.com/en/enterprise-server@3.19/admin/release-notes#3.19.10
    label: product-cna@github.com
  - url: >-
      https://docs.github.com/en/enterprise-server@3.20/admin/release-notes#3.20.6
    label: product-cna@github.com
  - url: >-
      https://docs.github.com/en/enterprise-server@3.21/admin/release-notes#3.21.4
    label: product-cna@github.com
tags:
  - nvd
  - cve.org
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-02T13:18:25.983888Z'
scores:
  nvd: 7.4
  cna: 8.2
epss: 0.00291
epssPercentile: 0.19313
ingestedAt: '2026-09-13T09:14:26.699Z'
---

## Overview

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 the outbound request could capture this token and replay it against privileged management agent endpoints. High-availability deployments were not affected due to a topology restriction. This vulnerability affected GitHub Enterprise Server releases in the 3.17, 3.18, 3.19, 3.20, and 3.21 series and was fixed in versions 3.17.21, 3.18.15, 3.19.12, 3.20.8, and 3.21.6. This vulnerability was reported via the GitHub Bug Bounty program.

## Affected

- `enterprise_server < 3.17.19`
- `enterprise_server >= 3.18.0, < 3.18.13`
- `enterprise_server >= 3.19.0, < 3.19.10`
- `enterprise_server >= 3.20.0, < 3.20.6`
- `enterprise_server >= 3.21.0, < 3.21.4`

## Remediation

Upgrade past the affected range:

- `enterprise_server 3.21.4`