Disclosing this banner is a poor security practice. It gives an attacker a complete "cheat sheet." It eliminates the need for them to probe or guess, instantly revealing the technology stack and signaling that the device likely has not been updated or hardened recently.
: Allows a remote, unauthenticated attacker to execute arbitrary commands with administrative privileges.
Many Cisco devices running the 1.25 stack are vulnerable to the , a prefix truncation weakness. ssh-2.0-cisco-1.25 vulnerability
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 core issue is a vulnerability in the SSHv2 implementation of Cisco IOS software. A crafted SSHv2 packet can cause the device to crash or reload. Disclosing this banner is a poor security practice
Disclaimer: The information in this article is based on publicly available Cisco Security Advisories and security research reports from 2023-2025.
Are you able to , or do you need a configuration-based workaround ? Knowing this will help us determine the best path forward. Share public link Many Cisco devices running the 1
Many devices identifying with this string are vulnerable to the Terrapin vulnerability (prefix truncation attack), which allows a Man-in-the-Middle (MitM) attacker to weaken the security of the connection.
The string breaks down into distinct components. The "SSH-2.0" prefix indicates that the server supports version 2.0 of the SSH protocol. The "Cisco" label identifies the vendor's proprietary implementation. The "1.25" suffix represents the internal version number of Cisco's SSH server code, not the version of the IOS operating system itself. This server version was particularly prevalent on devices running older software trains, where SSH functionality was often treated as a separate software component rather than a deeply integrated feature.