Ssh-2.0-cisco-1.25 Vulnerability

that a Cisco device sends when a connection is initiated over port 22. Cisco Community

Because this version is dated, it is frequently flagged by scanners because it supports weak cryptographic algorithms or is susceptible to protocol-level attacks discovered in recent years. Top Vulnerabilities Linked to This Version

The identifier is not a specific vulnerability itself, but rather the SSH banner string that many Cisco IOS and IOS XE devices use to identify their software version during an SSH handshake. When vulnerability scanners flag this string, they are typically reporting that the device is susceptible to a broader protocol-level flaw, most commonly the Terrapin Attack (CVE-2023-48795). What is the SSH-2.0-Cisco-1.25 "Vulnerability"?

For many legacy and current Cisco enterprise devices, this exposes SSH-2.0-Cisco-1.25 . This tells an analyst two things: ssh-2.0-cisco-1.25 vulnerability

The banner SSH-2.0-Cisco-1.25 is a historical marker that points to a legacy software stack that has been the source of several significant vulnerabilities. Understanding these issues is crucial for anyone maintaining older Cisco infrastructure.

However, the prevalence of this banner is significant because it signals the potential presence of various historical and modern critical vulnerabilities, including unpatched CVE-2002-1359 , the CVE-2015-0721 AAA bypass, and recent high-severity CVEs like CVE-2024-20526 . This article will dissect the technical nature of the SSH banner, analyze the critical vulnerabilities historically and currently associated with the device families that display it, and provide comprehensive mitigation strategies.

When a vulnerability scanner flags SSH-2.0-Cisco-1.25 , it means the scanner has detected a Cisco device running a generic or legacy version of Cisco’s internal SSH engine. Because this banner string remains identical across multiple firmware iterations, it can maps to several potential vulnerabilities depending on the specific underlying Cisco IOS release. that a Cisco device sends when a connection

The string is not a specific flaw itself, but rather the standardized software banner broadcasted by the Cisco IOS SSH server to establish cryptographic handshakes. Because this exact string maps to hundreds of thousands of active Enterprise routing and switching environments, threat actors look for this specific banner to identify target networks for a range of Cisco IOS and IOS XE SSH protocol flaws.

Security scanners do not flag ssh-2.0-cisco-1.25 as a vulnerability itself. They flag it because .

Use Access Control Lists (ACLs) to limit SSH access to known, trusted management IP addresses. When vulnerability scanners flag this string, they are

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.

ip ssh server algorithm encryption aes256-gcm aes128-gcm ip ssh server algorithm mac hmac-sha2-512 hmac-sha2-256 Use code with caution.

Understanding the "SSH-2.0-Cisco-1.25" Vulnerability Matrix: Risks, Technical Deep Dive, and Mitigation Strategies