Understanding the SSH-2.0-Cisco-1.25 Vulnerability: Risks, Identification, and Mitigation
If you’re doing or red teaming :
A significant vulnerability in the SSH version 2 protocol implementation allows unauthenticated, remote attackers to bypass user authentication. To exploit this, an attacker must know a valid username configured for RSA-based authentication. ssh-2.0-cisco-1.25 vulnerability
The Erlang/OTP SSH Remote Code Execution Flaw (CVE-2025-32433)
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. Understanding the SSH-2
The identifier is not a specific vulnerability itself, but rather the version banner that a Cisco device sends to identify its SSH software .
If SSH is not required and the device cannot be upgraded, disable the SSH service entirely and manage the device via console cable (out-of-band management) to remove the remote attack vector. line vty 0 15 no ip ssh pubkey-chain Use code with caution
Leaving older SSH versions exposed allows attackers to fingerprint your hardware and launch targeted exploits. The Cisco-1.25 software branch is associated with several historical vulnerabilities, depending on the underlying IOS version:
While often overlooked, this banner carries critical information about the device's software base and can be associated with specific security quirks, compatibility issues, and potential reconnaissance risks. This article provides a comprehensive analysis of the SSH-2.0-Cisco-1.25 banner, the nature of the underlying SSH server, its associated vulnerabilities, and the security implications for enterprise networks.
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.