The SSH-2.0-Cisco-1.25 string is frequently flagged by scanners such as Nessus or Shodan not necessarily because it has one single, catastrophic exploit, but because it is associated with several security weaknesses:
! Example Configuration Hardening ip ssh server algorithm encryption aes128-ctr aes192-ctr aes256-ctr ip ssh server algorithm mac hmac-sha2-256 hmac-sha2-512 ip ssh server algorithm kex diffie-hellman-group14-sha256 Use code with caution. 4. Implement Strict Access Control
To mitigate the SSH-2.0-Cisco-1.25 vulnerability, administrators should: ssh-2.0-cisco-1.25 vulnerability
| CVE | Description | Fixed in | |------|-------------|-----------| | | SSHv2 server DoS via crafted SSH packet → reload | IOS 15.1(2)T, 15.2(1)T | | CVE-2015-6274 | Algorithm negotiation bypass → weak encryption forced | IOS 15.4(3)M, 15.5(3)M | | CVE-2016-6376 | Memory exhaustion via multiple SSHv2 key exchanges | IOS 15.5(3)M3 | | CVE-2018-0151 | Remote code execution via SSHv2 (rare, but present in older banners) | IOS 15.6(3)M2 |
Resolving the SSH-2.0-Cisco-1.25 vulnerability requires updating the device’s software to a version that supports stronger encryption and more secure key exchanges. 1. Identify Affected Devices The SSH-2
: The device is utilizing version 1.25 of Cisco’s internal code package for handling secure shell connections.
Upgrade the device firmware to a supported release and regenerate RSA keys. Implement Strict Access Control To mitigate the SSH-2
: The Shodan CVE database provides detailed summaries of known vulnerabilities, including their CVSS scores and affected products, allowing for rapid correlation with discovered banners.
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.