Warning: Critical CVE-2026-77987 affects GitHub Enterprise Server, allowing attackers to exploit an SSRF vulnerability, potentially leading to remote code execution

GitHub Enterprise Server versions 3.17 through 3.22 are affected by CVE-2026-77987, a critical SSRF in the notebook viewer that fails to validate destination ports; an attacker can direct requests to internal services, use timing differences to extract instance secrets, and potentially escalate to remote code execution. Exploitation requires network access to the appliance and is unauthenticated when private mode is disabled; administrators are urged to apply updates and increase monitoring.