CVE-2026-50751 — Check Point Security Gateway: IKEv1 VPN authentication bypass, actively exploited by a Qilin affiliate

Check Point disclosed and patched CVE-2026-50751 (CVSS 9.3) on 8 June 2026 — a logic-flow weakness in certificate validation in the deprecated IKEv1 key exchange affecting Remote Access VPN and Mobile Access deployments. An unauthenticated remote attacker can establish a VPN session without a valid user password; post-authentication activity is still required to reach internal resources (Check Point, 2026-06-08). NCSC-CH issued an Action-Required advisory the same day and links observed exploitation to a Qilin ransomware affiliate (NCSC-CH, 2026-06-08); CISA added the CVE to its KEV catalog on 8 June. Full technical treatment, exploitation prerequisites and hardening are in § 5 below. The companion CVE-2026-50752 (CVSS 7.4, site-to-site IKEv1 MitM, no observed exploitation) should be patched in the same window.