EXPOSURES › CVE-2026-77987
CVE-2026-77987
CRITICALGitHub Enterprise Server's notebook viewer allowed SSRF to internal services, enabling secret extraction and remote code execution.
The notebook viewer failed to validate the port of user-supplied URLs, allowing SSRF to internal services. Extracted secrets enabled remote code execution on the appliance. DIB orgs must ensure their GitHub Enterprise Server is patched and that SSRF protections are validated across all internal-facing services.
Shame score — A critical SSRF flaw in a widely-used enterprise platform allowed unauthenticated or low-privilege access to internal services and remote code execution, demonstrating severe validation gaps in a core developer tool.
▸ RECOMMENDED ACTION Remote code execution — patch the affected products on priority.
A server-side request forgery (SSRF) vulnerability was identified in the notebook viewer of GitHub Enterprise Server. The notebook viewer validated the scheme and host of a user-supplied URL but did not validate the port, allowing requests to be directed to internal services listening on other ports of the same appliance. Response bodies were not returned to the requester, but response timing acted as an oracle that allowed instance secrets to be extracted character by character. An extracted secret could then be used in a separate interaction with an internal service to obtain remote code execution on the appliance. Exploitation required network access to the instance and was unauthenticated when private mode was disabled, or required any authenticated user when private mode was enabled. This vulnerability affected GitHub Enterprise Server versions 3.17 through 3.22 and was fixed in versions 3.22.1, 3.21.6, 3.20.8, 3.19.12, 3.18.15, and 3.17.21. This vulnerability was reported through the GitHub Bug Bounty program.
| PRODUCT | STATUS |
|---|---|
| GitHub Enterprise Cloud GitHub |
Authorized |