Pre-authentication Denial of Service attack in OpenSSH - CVE-2025-26466 Fortinet PSIRT Advisories Fortinet PSIRT Contact: Website: https://fortiguard.fortinet.com/faq/psirt-contact FG-IR-25-122 Final 1 1 2025-03-11T00:00:00 Current version 2025-03-11T00:00:00 2026-03-04T00:00:00 CVE-2025-26466A flaw was found in the OpenSSH package. For each ping packet the SSH server receives, a pong packet is allocated in a memory buffer and stored in a queue of packages. It is only freed when the server/client key exchange has finished. A malicious client may keep sending such packages, leading to an uncontrolled increase in memory consumption on the server side. Consequently, the server may become unavailable, resulting in a denial of service attack. None Denial of service https://fortiguard.fortinet.com/psirt/FG-IR-25-122 Pre-authentication Denial of Service attack in OpenSSH - CVE-2025-26466 https://nvd.nist.gov/vuln/detail/CVE-2025-26466 https://nvd.nist.gov/vuln/detail/CVE-2025-26466 https://www.qualys.com/2025/02/18/openssh-mitm-dos.txt https://www.qualys.com/2025/02/18/openssh-mitm-dos.txt FortiADC 7.6.1 FortiADCManager 7.6.0 FortiAIOps 2.1.0 FortiAIOps 2.0.2 FortiAIOps 2.0.1 FortiAnalyzer 7.6.2 FortiAnalyzer 7.6.1 FortiAnalyzer 7.6.0 FortiAnalyzer 7.4.6 FortiAnalyzer 7.4.5 FortiAnalyzer 7.4.4 FortiAnalyzer 7.4.3 FortiAnalyzer 7.2.10 FortiAnalyzer 7.2.9 FortiAnalyzer 7.2.8 FortiAnalyzer 7.2.7 FortiAnalyzer 7.2.6 FortiAnalyzer 7.2.5 FortiAnalyzer 7.0.16 FortiAnalyzer 7.0.15 FortiAnalyzer 7.0.14 FortiAnalyzer 7.0.13 FortiAnalyzer 7.0.12 FortiAnalyzer 6.4.15 FortiAnalyzer 6.4.14 FortiAnalyzer-BigData 7.4.3 FortiAnalyzer-BigData 7.4.2 FortiAnalyzer-BigData 7.2.9 FortiAnalyzer-BigData 7.2.8 FortiDDoS-F 7.0.4 FortiDDoS-F 7.0.3 FortiDDoS-F 7.0.2 FortiDDoS-F 7.0.1 FortiExtender 7.6.2 FortiExtender 7.6.1 FortiExtender 7.6.0 FortiExtender 7.4.7 FortiExtender 7.4.6 FortiExtender 7.4.5 FortiExtender 7.4.4 FortiExtender 7.2.5 FortiExtender 7.0.5 FortiManager 7.6.2 FortiManager 7.6.1 FortiManager 7.6.0 FortiManager 7.4.6 FortiManager 7.4.5 FortiManager 7.4.4 FortiManager 7.4.3 FortiManager 7.2.10 FortiManager 7.2.9 FortiManager 7.2.8 FortiManager 7.2.7 FortiManager 7.2.6 FortiManager 7.2.5 FortiManager 7.0.16 FortiManager 7.0.15 FortiManager 7.0.14 FortiManager 7.0.13 FortiManager 7.0.12 FortiManager 6.4.15 FortiManager 6.4.14 FortiNDR 7.6.1 FortiNDR 7.6.0 FortiNDR 7.4.8 FortiNDR 7.4.7 FortiNDR 7.4.6 FortiNDR 7.4.5 FortiNDR 7.4.4 FortiNDR 7.4.3 FortiNDR 7.2.5 FortiNDR 7.2.4 FortiNDR 7.2.3 FortiNDR 7.2.2 FortiNDR 7.0.7 FortiNDR 7.0.6 FortiSandbox 5.0.1 FortiSandbox 5.0.0 FortiSandbox 4.4.7 FortiSandbox 4.4.6 FortiSandbox 4.4.5 FortiSandbox 4.4.4 FortiSandbox 4.2.8 FortiSandbox 4.2.7 FortiSwitch 7.6.4 FortiSwitch 7.6.3 FortiSwitch 7.6.2 FortiSwitch 7.6.1 FortiSwitch 7.6.0 FortiSwitch 7.4.7 FortiSwitch 7.4.6 FortiSwitch 7.4.5 FortiSwitch 7.4.4 FortiSwitch 7.2.10 FortiSwitch 7.2.9 FortiSwitch 7.2.8 FortiVoice 7.2.1 FortiVoice 7.2.0 FortiVoice 7.0.7 FortiVoice 7.0.6 FortiVoice 7.0.5 FortiVoice 7.0.4 FortiVoice 7.0.3 FortiVoice 7.0.2 FortiVoice 6.4.11 FortiVoice 6.4.10 FortiVoice 6.4.9 FortiWeb 7.6.4 FortiWeb 7.6.3 FortiWeb 7.6.2 FortiWeb 7.6.1 FortiWeb 7.6.0 FortiWeb 7.4.8 FortiWeb 7.4.7 FortiWeb 7.4.6 FortiWeb 7.4.5 FortiWeb 7.4.4 FortiWeb 7.4.3 FortiWeb 7.2.12 FortiWeb 7.2.11 FortiWeb 7.2.10 FortiWeb 7.2.9 FortiWeb 7.2.8 CVE-2025-26466 FortiADC-7.6.1 FortiADCManager-7.6.0 FortiAIOps-2.1.0 FortiAIOps-2.0.2 FortiAIOps-2.0.1 FortiAnalyzer-7.6.2 FortiAnalyzer-7.6.1 FortiAnalyzer-7.6.0 FortiAnalyzer-7.4.6 FortiAnalyzer-7.4.5 FortiAnalyzer-7.4.4 FortiAnalyzer-7.4.3 FortiAnalyzer-7.2.10 FortiAnalyzer-7.2.9 FortiAnalyzer-7.2.8 FortiAnalyzer-7.2.7 FortiAnalyzer-7.2.6 FortiAnalyzer-7.2.5 FortiAnalyzer-7.0.16 FortiAnalyzer-7.0.15 FortiAnalyzer-7.0.14 FortiAnalyzer-7.0.13 FortiAnalyzer-7.0.12 FortiAnalyzer-6.4.15 FortiAnalyzer-6.4.14 FortiAnalyzer-BigData-7.4.3 FortiAnalyzer-BigData-7.4.2 FortiAnalyzer-BigData-7.2.9 FortiAnalyzer-BigData-7.2.8 FortiDDoS-F-7.0.4 FortiDDoS-F-7.0.3 FortiDDoS-F-7.0.2 FortiDDoS-F-7.0.1 FortiExtender-7.6.2 FortiExtender-7.6.1 FortiExtender-7.6.0 FortiExtender-7.4.7 FortiExtender-7.4.6 FortiExtender-7.4.5 FortiExtender-7.4.4 FortiExtender-7.2.5 FortiExtender-7.0.5 FortiManager-7.6.2 FortiManager-7.6.1 FortiManager-7.6.0 FortiManager-7.4.6 FortiManager-7.4.5 FortiManager-7.4.4 FortiManager-7.4.3 FortiManager-7.2.10 FortiManager-7.2.9 FortiManager-7.2.8 FortiManager-7.2.7 FortiManager-7.2.6 FortiManager-7.2.5 FortiManager-7.0.16 FortiManager-7.0.15 FortiManager-7.0.14 FortiManager-7.0.13 FortiManager-7.0.12 FortiManager-6.4.15 FortiManager-6.4.14 FortiNDR-7.6.1 FortiNDR-7.6.0 FortiNDR-7.4.8 FortiNDR-7.4.7 FortiNDR-7.4.6 FortiNDR-7.4.5 FortiNDR-7.4.4 FortiNDR-7.4.3 FortiNDR-7.2.5 FortiNDR-7.2.4 FortiNDR-7.2.3 FortiNDR-7.2.2 FortiNDR-7.0.7 FortiNDR-7.0.6 FortiSandbox-5.0.1 FortiSandbox-5.0.0 FortiSandbox-4.4.7 FortiSandbox-4.4.6 FortiSandbox-4.4.5 FortiSandbox-4.4.4 FortiSandbox-4.2.8 FortiSandbox-4.2.7 FortiSwitch-7.6.4 FortiSwitch-7.6.3 FortiSwitch-7.6.2 FortiSwitch-7.6.1 FortiSwitch-7.6.0 FortiSwitch-7.4.7 FortiSwitch-7.4.6 FortiSwitch-7.4.5 FortiSwitch-7.4.4 FortiSwitch-7.2.10 FortiSwitch-7.2.9 FortiSwitch-7.2.8 FortiVoice-7.2.1 FortiVoice-7.2.0 FortiVoice-7.0.7 FortiVoice-7.0.6 FortiVoice-7.0.5 FortiVoice-7.0.4 FortiVoice-7.0.3 FortiVoice-7.0.2 FortiVoice-6.4.11 FortiVoice-6.4.10 FortiVoice-6.4.9 FortiWeb-7.6.4 FortiWeb-7.6.3 FortiWeb-7.6.2 FortiWeb-7.6.1 FortiWeb-7.6.0 FortiWeb-7.4.8 FortiWeb-7.4.7 FortiWeb-7.4.6 FortiWeb-7.4.5 FortiWeb-7.4.4 FortiWeb-7.4.3 FortiWeb-7.2.12 FortiWeb-7.2.11 FortiWeb-7.2.10 FortiWeb-7.2.9 FortiWeb-7.2.8 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H/E:X/RL:O/RC:X https://fortiguard.fortinet.com/psirt/FG-IR-25-122 Pre-authentication Denial of Service attack in OpenSSH - CVE-2025-26466 Reference> https://nvd.nist.gov/vuln/detail/CVE-2025-26466 https://nvd.nist.gov/vuln/detail/CVE-2025-26466 https://www.qualys.com/2025/02/18/openssh-mitm-dos.txt https://www.qualys.com/2025/02/18/openssh-mitm-dos.txt