Ssh-2.0-cisco-1.25 Vulnerability [upd] Jun 2026

SSH-2.0-Cisco-1.25 │ │ │ │ │ │ │ └── Sub-version / Internal Patch Level (1.25) │ │ └──────── Software Vendor / Implementation Name (Cisco) │ └──────────── Protocol Version (SSHv2 standard compatibility) └──────────────── Protocol Identifier (Required prefix)

The vulnerability affects devices configured for RSA-based user authentication (public key).

The most effective solution is to upgrade the Cisco IOS or IOS-XE software to a patched, recommended release. Review the for the latest recommendations on SSH vulnerabilities. 3. Disable Weak Cryptographic Algorithms

The SSH-2.0-Cisco-1.25 vulnerability is caused by a buffer overflow in the SSH protocol implementation. An attacker can exploit this vulnerability by sending a specially crafted SSH packet to the device, which can lead to: ssh-2.0-cisco-1.25 vulnerability

Cisco has released bug fixes (e.g., CSCwi61646 for Catalyst switches) that implement a "strict key exchange" to block this attack. 2. Critical Remote Code Execution (CVE-2025-32433)

The most effective fix is to upgrade to a modern, patched version of Cisco software. Check the Cisco Security Advisory for your specific hardware to find the recommended "Gold Star" release. Step 2: Harden the SSH Configuration

The SSH-2.0-Cisco-1.25 vulnerability is a weakness in the Cisco SSH implementation that allows an attacker to exploit the server's authentication mechanism. Specifically, the vulnerability occurs when the server is configured to use a specific type of authentication, known as "keyboard-interactive" authentication. how attackers scan for it

This is a "prefix truncation" attack where a man-in-the-middle (MitM) attacker can secretly remove parts of the encrypted handshake.

Understanding the security risks associated with this banner requires an examination of the flaws it exposes, how attackers scan for it, and the necessary remediation techniques. What Does the SSH-2.0-Cisco-1.25 Banner Mean?

The underlying SSH server implementation might use deprecated cryptographic algorithms or weak key exchange methods (e.g., Diffie-Hellman Group1). ssh-2.0-cisco-1.25 vulnerability

SSH0: Exchanging versions - SSH-2.0-Cisco-1.25 SSH0: send SSH message: outdated is NULL server version string:SSH-2.0-Cisco-1.25

When an SSH client connects to a server, the server first sends a version string to identify itself. The SSH-2.0-Cisco-1.25 string tells the client: "I am a Cisco device running my own SSH server (version 1.25) and I speak the SSH-2 protocol".

The vulnerability fingerprint disappears only when you upgrade to a patched Cisco IOS/NX-OS release.