SSRF in GitHub Enterprise Server (3.21.1) via Packages Advisories Lookup
CVE-2026-8606 Published on May 26, 2026
Server-Side Request Forgery in GitHub Enterprise Server via Advisory Package URL Endpoint
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 Analysis
CVE-2026-8606 is exploitable with network access, and does not require authorization privileges or user interaction. This vulnerability is consided to have a high level of attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity and availability.
Weakness Type
What is a SSRF Vulnerability?
The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination. By providing URLs to unexpected hosts or ports, attackers can make it appear that the server is sending the request, possibly bypassing access controls such as firewalls that prevent the attackers from accessing the URLs directly. The server can be used as a proxy to conduct port scanning of hosts in internal networks, use other URLs such as that can access documents on the system (using file://), or use other protocols such as gopher:// or tftp://, which may provide greater control over the contents of requests.
CVE-2026-8606 has been classified to as a SSRF vulnerability or weakness.
Products Associated with CVE-2026-8606
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Affected Versions
GitHub Enterprise Server:- Version 3.21.0 and below 3.21.1 is affected.
- Version 3.20.0, <= 3.20.2 is affected.
- Version 3.19.0, <= 3.19.6 is affected.
- Version 3.18.0, <= 3.18.9 is affected.
- Version 3.17.0, <= 3.17.15 is affected.
- Version 3.16.0, <= 3.16.18 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.