The attacker must know a valid username and its associated public key. Remediation:
While modern Cisco NX-OS and IOS XE have faced their own SSH-related vulnerabilities—such as CVE-2023-20050 and CVE-2022-20920—the era vulnerability is distinct because of its legacy nature.
Older deployments of Cisco IOS often retain backward compatibility with insecure hashing algorithms and symmetric ciphers. If an SSH server is configured to accept legacy parameters, remote attackers can perform machine-in-the-middle (MitM) resource degradation or attempt cryptographic breaks on data packets in transit. ssh20cisco125 vulnerability exclusive
Although this vulnerability carries a lower CVSS score, its unique exploitation vector makes it noteworthy. (disclosed March 2026) affects the proprietary SSH stack with SSH key-based authentication in Cisco Secure Firewall ASA Software.
[Administrator Client] <====== (Intercepted SSH Session) ======> [Attacker MitM Proxy] || (Injected Commands) || \/ [Compromised Cisco Switch] The attacker must know a valid username and
These features should help you identify and remediate the SSH-2-Cisco-1.25 vulnerability on your Cisco devices.
Instead of safely dropping these invalid packets, the device's SSH subsystem experiences an internal logic error. This places the SSH state machine into an unhandled configuration. If an SSH server is configured to accept
: Denotes that the target system is actively running Cisco SSH Version 2 . While SSHv2 is structurally secure compared to the obsolete SSHv1 protocol, its security depends entirely on implementation, user authentication methods, and robust access lists.
Mitigate resource exhaustion and denial-of-service attempts by tightening the authentication window and terminating idle administrative sessions.
Explicitly configure your devices to reject legacy connection protocols and enforce strong, modern encryption algorithms.