What is 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.
The record classifies CVE-2026-8606 under weakness class CWE-918. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on confidentiality. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 132 days ago.
Severity and exploitation probability
- CVSS v3.1 base score
- 5.9 — MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N - CVSS v4.0 base score
- 7
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:H/SI:H/SA:N - EPSS (FIRST)
- 0.0% probability of exploitation in the next 30 days, higher than 22.8% of all scored CVEs
- CISA KEV
- Not listed in the CISA Known Exploited Vulnerabilities catalog
- Threadlinqs priority
- 3.9/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- Published
- 2026-05-26, last modified 2026-05-27
Is CVE-2026-8606 being exploited?
It currently carries a trending score of 11 in the Threadlinqs vulnerability feed.
Affected products and versions
- Github: Enterprise Server
How to fix CVE-2026-8606
No vendor patch reference has been recorded for CVE-2026-8606 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.
Threat activity tracking CVE-2026-8606
1 tracked threat in the Threadlinqs corpus references CVE-2026-8606, either in the campaign’s CVE list or as an indicator on the campaign record.
Sources
Seeded from cveorg and not yet processed by the Threadlinqs enrichment pipeline, so blank CVSS, EPSS or KEV fields above mean NOT MEASURED rather than measured-absent.