The most common critical finding for this specific version is the preference for the Diffie-Hellman Group 1 (diffie-hellman-group1-sha1) key exchange.
The identification of Cisco-1.25 suggests the device is utilizing an older SSH implementation library. Below are the primary vulnerabilities associated with this specific banner.
Devices reporting SSH-2.0-Cisco-1.25 are often running software that has reached End-of-Life. This means they no longer receive security patches for newly discovered vulnerabilities, making them a persistent security liability. ssh-2.0-cisco-1.25 vulnerability
In a penetration test or real attack, glimpsing SSH-2.0-Cisco-1.25 is gold. Here is how an attacker would proceed:
In one documented 2019 incident, a threat actor used Shodan to locate a municipal water utility’s Cisco router running SSH-2.0-Cisco-1.25. They triggered a DoS vulnerability remotely, taking the SCADA network offline for six hours. The most common critical finding for this specific
Vulnerabilities are assigned a CVE ID by MITRE. No CVE uses the string ssh-2.0-cisco-1.25. Security tools that flag this banner as a “critical vulnerability” are using outdated or heuristic signatures. The banner only indicates:
When an SSH client connects to a server, the server sends a "banner" identifying its software version. In this case, the string breaks down as follows: In a penetration test or real attack, glimpsing SSH-2
The version "1.25" is archaic. It dates back to early Cisco IOS (Internetwork Operating System) implementations from the early-to-mid 2000s. While modern Cisco devices run much newer SSH implementations, seeing this specific version string in 2023/2024 is an immediate red flag. It suggests the device is running an operating system that has not been updated in potentially two decades.
The banner SSH-2.0-Cisco-1.25 is not a vulnerability in itself, but a clue. Security analysts should avoid treating banners as CVEs. Instead, they should use banner data to guide targeted, authenticated testing. A device showing this banner — particularly if it maps to IOS 12.2(25) — may be vulnerable to several historical SSH issues, but each requires independent verification.