Ssh-2.0-cisco-1.25 Vulnerability High Quality -
Ssh-2.0-cisco-1.25 Vulnerability High Quality -
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?
To mitigate the SSH-2.0-Cisco-1.25 vulnerability, administrators should:
Beyond the SSHredder class, Cisco's SSH stack has a history of vulnerabilities that primarily lead to DoS conditions, causing device reloads.
implementation allows a remote attacker to bypass authentication. By using a crafted private key, an attacker could log in with the privileges of the targeted user or the Virtual Teletype (VTY) line. ssh-2.0-cisco-1.25 vulnerability
Because Cisco embeds this software subsystem directly into the kernel of various IOS versions, upgrading the core operating system is usually required to modify or change this identifier string. Key Historical and Modern Vulnerabilities
Many Cisco devices running the 1.25 stack are vulnerable to the , a prefix truncation weakness.
Resolving the risks associated with this banner requires a multi-layered security approach. Step 1: Upgrade Cisco IOS/IOS-XE Understanding the security risks associated with this banner
: A prefix truncation weakness that allows a man-in-the-middle (MitM) attacker to downgrade connection security by bypassing integrity checks. Cisco Community Denial of Service (DoS) SSH Terrapin Prefix Truncation Weakness - Cisco Community 12 Jan 2024 —
: Recent reports in April 2025 highlight a critical RCE vulnerability in the Erlang-based SSH server used in some Cisco product lines. This is a "Perfect 10" severity flaw that allows unauthenticated code execution. Cisco Community How to Verify and Mitigate SSH Terrapin Prefix Truncation Weakness - Cisco Community
: Confirms that the target device uses the Secure Shell Version 2 framework. Cisco : Identifies the device vendor. Key Historical and Modern Vulnerabilities Many Cisco devices
The theoretical risks associated with this banner have transitioned into real-world, high-stakes attacks. In 2025, cybersecurity agencies, including CISA in the United States, issued emergency directives regarding critical zero-day vulnerabilities in Cisco ASA and Secure Firewall appliances. These vulnerabilities, tracked as CVE-2025-20333 and CVE-2025-20362, were leveraged by advanced threat actors to implant malware on vulnerable devices.
The identification string SSH-2.0-Cisco-1.25 is a common sight for network engineers, appearing during SSH connections to a vast number of Cisco switches and routers. It is not merely a version number; it's a digital banner announced by the SSH server on a device as soon as a TCP connection is established on port 22.
Historically, when security teams or automated compliance scanners flag an "SSH-2.0-Cisco-1.25 vulnerability," they are generally targeting severe software vulnerabilities tied to specific Cisco platform code. Most notably, this includes the high-severity (CVE-2025-32433), alongside classic architectural issues like authentication bypasses (CVE-2015-0235/related flaws) and state-machine Denials of Service (CVE-2020-3200). Technical Background: What is the Cisco-1.25 Banner?
On Cisco ASA devices that reported similar version strings (often overlapping with 1.25 ), there was a vulnerability where processing specific SSH packets would not free memory correctly. Over days or weeks, the device would exhaust memory and stop passing traffic. This required a reboot to resolve.
: Restrict the volume of SSH traffic that the device's central route processor accepts. This directly minimizes the risk of state-exhaustion and DoS attacks.