Ssh-2.0-cisco-1.25 Vulnerability [upd] -
: The device runs into an unhandled exception state and triggers a forced system reload, generating a sustained Denial of Service (DoS) window across the production environment. 3. RSA-Based Public Key Authentication Bypass
If an immediate software upgrade is not possible due to hardware limitations, apply the following configurations on the Cisco device:
nmap --script ssh2-enum-algos -p 22 <target> nmap --script ssh-hostkey --script-args ssh_hostkey=all -p 22 <target>
The string SSH-2.0-Cisco-1.25 is a software version banner identifying the Secure Shell (SSH) server implementation used by a wide variety of Cisco products, including Catalyst switches ISR routers ASA firewalls ssh-2.0-cisco-1.25 vulnerability
Security teams must shift from simply noting the banner's presence to aggressively . The persistence of this banner on the public internet serves as a stark reminder: in network security, what you choose to reveal about your infrastructure can be your first and most exploitable vulnerability.
[Detect Banner] -> [Verify Software with Cisco Checker] -> [Apply ACLs] -> [Deploy Software Update] Step 1: Query the Internal Firmware Version
If encryption is weakened, attackers might be able to hijack administrative sessions. : The device runs into an unhandled exception
Weak algorithms could allow for the decryption of session data.
Security research reports from April 2025 highlighted significant global exposure for devices identifying as "SSH-2.0-Cisco-1.25". Approximately 92,000 exposed instances found. Censys: Over 103,000 instances identified. FOFA: Up to 309,000 instances detected. Related Historical Vulnerabilities
Older Cisco IOS releases using SSH with TACACS+ authentication are vulnerable to resource exhaustion, which can lead to spontaneous reloads. Scope and Exposure The persistence of this banner on the public
In the world of network security, few things cause a spike in adrenaline quite like an unfamiliar banner appearing in your vulnerability scanner. For many system administrators and security analysts, the string is one such trigger. Scrolling through a Nessus, OpenVAS, or Qualys report, this identifier often appears under "SSH Server Version Information," flagged with a medium or high-severity warning.
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
: Designates that the cryptographic daemon running on the system is Cisco's own internal implementation, as opposed to third-party open-source alternatives like OpenSSH or Dropbear .
Consult the Cisco Security Advisories page to identify the fixed release for your specific hardware.
