CVE-2026-8606: enterprise server SSRF (CVSS 5.9)

Description

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.

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CVSS v3.1 Score

5.9

MEDIUM

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

EPSS — Exploit Prediction

0.0039

Probability of exploitation

0.30%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-918 Server-Side Request Forgery (SSRF)

Affected Products

Vendor	Product	Versions
github	enterprise_server	< 3.16.19
github	enterprise_server	3.17.0 — 3.17.16
github	enterprise_server	3.18.0 — 3.18.10
github	enterprise_server	3.19.0 — 3.19.7
github	enterprise_server	3.20.0 — 3.20.3
github	enterprise_server	All

References

Other References

https://docs.github.com/en/[email protected]/admin/release-notes#3.16.19 https://docs.github.com/en/[email protected]/admin/release-notes#3.17.16 https://docs.github.com/en/[email protected]/admin/release-notes#3.18.10 https://docs.github.com/en/[email protected]/admin/release-notes#3.19.7 https://docs.github.com/en/[email protected]/admin/release-notes#3.20.3 https://docs.github.com/en/[email protected]/admin/release-notes#3.21.1

Frequently Asked Questions

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. It has a CVSS v3.1 base score of 5.9 (MEDIUM).

How severe is CVE-2026-8606? +

CVE-2026-8606 has a CVSS v3.1 score of 5.9 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0039, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-8606? +

CVE-2026-8606 affects products from github, specifically: enterprise_server. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-8606? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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