Ssh-2.0-cisco-1.25 Vulnerability [2026]

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.

The banner SSH-2.0-Cisco-1.25 is a standard version string identifying the Secure Shell (SSH) server running on many

0 Helpful. Georg Pauwen. VIP Alumni. ‎02-16-2021 12:30 AM. Hello, I think the '1.25' part is the Cisco specific vendor version ID. Cisco Community SSH Terrapin Prefix Truncation Weakness - Cisco Community ssh-2.0-cisco-1.25 vulnerability

To help evaluate the risk posture of your device,Additionally, knowing if your device is or directly exposed to the internet will help tailor the exact patch path. Share public link

However, "Cisco-1.25" is found across many different IOS versions. Depending on which IOS version you are running, your device might be vulnerable to several real, documented threats: SSH Terrapin Prefix Truncation Weakness - Cisco Community Disclosing this banner is a poor security practice

: A man-in-the-middle (MitM) prefix truncation weakness. By intercepting the handshake, an attacker can silently delete or alter packet sequences during the initial exchange without breaking cryptographic integrity checks.

A critical vulnerability (CVSS 9.9) was also discovered in the SSH subsystem of Cisco ASA and Firepower Threat Defense (FTD) Software. This issue, due to insufficient input validation, allowed an authenticated, remote attacker to execute commands on the underlying operating system with by sending crafted input during SSH sessions. Georg Pauwen

The SSH-2.0-Cisco-1.25 banner is a sign of potentially dangerous exposure. While it typically indicates older software, the threat is current, with thousands of devices remaining unpatched and vulnerable to remote exploitation. Organizations using Cisco equipment must prioritize scanning for this banner and applying the necessary software updates to protect their network infrastructure.

: An attacker can establish a standard SSH session and transmit a carefully crafted sequence of malformed packets. Instead of dropping the corrupted packets, the engine triggers an unexpected internal error, causing the entire device to reload or crash, leading to a network-wide Denial of Service. 3. Cryptographic Downgrade and Terrapin Attacks