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CVE-2026-18730

Enterprise Server · Vulnerability

CVSS 4.0 8.2 HIGHCheck source for fixed versionsKEV status unknown

Original advisory

cve-program · CVE-2026-18730

Published

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.

Read the publisher's advisory

Affected versions, risk and source history

cve-program · CVE-2026-18730

Published

Enterprise Server

Vendor product

Publisher's version information

Shown as published. These rules are not interpreted as NuGet package version ranges.

{
                    "vendor": "GitHub",
                    "product": "Enterprise Server",
                    "versions": [
                        {
                            "status": "affected",
                            "version": "3.17.0",
                            "lessThan": "3.17.*",
                            "changes": [
                                {
                                    "at": "3.17.21",
                                    "status": "unaffected"
                                }
                            ],
                            "versionType": "semver"
                        },
                        {
                            "status": "affected",
                            "version": "3.18.0",
                            "lessThan": "3.18.*",
                            "changes": [
                                {
                                    "at": "3.18.15",
                                    "status": "unaffected"
                                }
                            ],
                            "versionType": "semver"
                        },
                        {
                            "status": "affected",
                            "version": "3.19.0",
                            "lessThan": "3.19.*",
                            "changes": [
                                {
                                    "at": "3.19.12",
                                    "status": "unaffected"
                                }
                            ],
                            "versionType": "semver"
                        },
                        {
                            "status": "affected",
                            "version": "3.20.0",
                            "lessThan": "3.20.*",
                            "changes": [
                                {
                                    "at": "3.20.8",
                                    "status": "unaffected"
                                }
                            ],
                            "versionType": "semver"
                        },
                        {
                            "status": "affected",
                            "version": "3.21.0",
                            "lessThan": "3.21.*",
                            "changes": [
                                {
                                    "at": "3.21.6",
                                    "status": "unaffected"
                                }
                            ],
                            "versionType": "semver"
                        }
                    ],
                    "defaultStatus": "unknown"
                }

Original source record · Cite this exact observation · Complete original publisher JSON