CVE-2026-18730: Server-side request forgery vulnerability in GitHub Enterprise Server Manage API leaked a replayable gateway-agent bearer token

1. In CISA KEV: not seen
2. Exploited (reported): not seen
3. Scanning observed: not seen
4. Proof of concept public: not seen
5. Not establishedNothing in the sources we check

DescriptionNVD

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.

Exploitation

Unlikely (under 1%). EPSS under 1%, or no score yet.

CISA KEV

Not listed

Public check

No public nuclei template

Weakness

Server-Side Request Forgery

Vendor

GitHub

Published

September 2026

Band

Unlikely (under 1%), September 2026

• NVD entrynvd.nist.gov
• Vendor advisorydocs.github.com
• CVE recordcve.org
• Weakness CWE-918cwe.mitre.org