SSRF in GitHub Enterprise Server
CVE-2026-8606
A Server-Side Request Forgery (SSRF) vulnerability was identified in GitHub Enterprise Server that allowed an attacker to cause the server to issue HTTP requests to internal services via the security advisories package lookup feature. By directing requests to an internal management service and measuring response timing, an attacker could infer the values of sensitive environment variables, including signing secrets and private keys. Exploitation required GitHub Packages to be enabled; on instances not running in private mode the vulnerability was exploitable without authentication, otherwise any authenticated user could exploit it. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.21.1 and was fixed in versions 3.20.3, 3.19.7, 3.18.10, 3.17.16, and 3.16.19. This vulnerability was reported via the GitHub Bug Bounty program.
Vulnerability class: SSRF (Server-Side Request Forgery)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N.
EPSS exploit prediction
EPSS: 0.007 (51.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 51st percentile — 51.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.007 · change: +0.002
Affected products
- GitHub Enterprise Server — versions 3.21.0, 3.20.0, 3.19.0
- GitHub Enterprise Server — versions 3.21.0
Weakness classification (CWE)
References
- docs.github.com/en/enterprise-server@3.16/admin/release-notes (release-notes, Product, Release Notes)
- docs.github.com/en/enterprise-server@3.17/admin/release-notes (release-notes, Product, Release Notes)
- docs.github.com/en/enterprise-server@3.18/admin/release-notes (release-notes, Product, Release Notes)
- docs.github.com/en/enterprise-server@3.19/admin/release-notes (release-notes, Product, Release Notes)
- docs.github.com/en/enterprise-server@3.20/admin/release-notes (release-notes, Product, Release Notes)
- docs.github.com/en/enterprise-server@3.21/admin/release-notes (release-notes, Product, Release Notes)
Frequently asked questions
- What is CVE-2026-8606?
- CVE-2026-8606 is a medium-severity vulnerability in GitHub Enterprise Server, classified under Server-Side Request Forgery (SSRF). CVSS score: 5.9/10. Published 2026-05-27.
- How severe is CVE-2026-8606?
- Medium severity. CVSS v3 base score is 5.9 out of 10.