The impact of the SSH-2.0-Cisco-1.25 vulnerability is significant. If exploited, an attacker could:
: Recent reports in April 2025 highlight a critical RCE vulnerability in the Erlang-based SSH server used in some Cisco product lines. This is a "Perfect 10" severity flaw that allows unauthenticated code execution. Cisco Community How to Verify and Mitigate SSH Terrapin Prefix Truncation Weakness - Cisco Community
The SSH banner SSH-2.0-Cisco-1.25 is often misinterpreted as a specific vulnerability. This paper clarifies that this string is a version identifier, not a CVE entry. We map this banner to potential Cisco software versions, review historical SSH-related vulnerabilities in Cisco IOS/IOS-XE, and provide a methodology for determining actual exposure. We conclude that security assessments must go beyond banner grabbing and incorporate authenticated version checks and patch-level verification.
Your path forward is clear:
If an immediate patch is not possible, temporarily disable RSA-based authentication on the VTY lines. line vty 0 15 no ip ssh pubkey-chain Use code with caution.
show ip ssh
The SSH-2.0-Cisco-1.25 banner acts as a marker for a wide range of underlying security vulnerabilities in Cisco's SSH implementation. ssh-2.0-cisco-1.25 vulnerability
Disclaimer: The information in this article is based on publicly available Cisco Security Advisories and security research reports from 2023-2025.
: A Man-in-the-Middle (MitM) attacker can downgrade the connection's security by deleting specific protocol messages during the handshake without the client or server noticing. Cisco Bug ID : CSCwi61646 . 2. Unauthenticated Remote Code Execution (CVE-2025-32433)
If it connects without warning → vulnerable. The impact of the SSH-2
Router(config)# ip ssh server algorithm encryption aes256-ctr aes192-ctr aes128-ctr Router(config)# ip ssh server algorithm mac hmac-sha2-256 hmac-sha2-512 Use code with caution. Step 3: Restrict Access via Access Control Lists (ACLs)
nmap --script ssh2-enum-algos -p 22 <target> nmap --script ssh-hostkey --script-args ssh_hostkey=all -p 22 <target>