Ssh-2.0-cisco-1.25 Vulnerability Jun 2026

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

If an upgrade is not immediately possible, you can harden the existing configuration by disabling weak algorithms and key exchanges:

For older Cisco environments, indicates that the device mandates the secure SSH version 2.0 protocol while operating on an older internal Cisco SSH code branch ( Cisco-1.25 ). Security scanning engines parse this plaintext banner during passive reconnaissance to match the asset against historically documented vulnerabilities. Associated Historical Vulnerabilities

: The device must be configured for RSA-based user authentication. Remote Code Execution (CVE-2025-32433)

Before applying fixes, you must identify which devices are exposing this banner. 1. Manual Verification via CLI 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

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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".

To prevent similar vulnerabilities in the future, administrators should: The most effective fix is to upgrade to

The string SSH-2.0-Cisco-1.25 is not a specific vulnerability itself, but rather the version banner

By combining software updates with strict configuration hardening, you can successfully protect your infrastructure from exploits targeting legacy Cisco SSH versions.

When security professionals discuss the "Cisco-1.25 vulnerability," they are typically referring to one of the following critical issues: 1. The Terrapin Attack (CVE-2023-48795)

If your device reports this version string, it may be affected by the following vulnerabilities depending on the specific software release (IOS/IOS-XE): RSA-Based Authentication Bypass (CVE-2015-6280) Security scanning engines parse this plaintext banner during

Certain legacy Cisco SSH implementations suffer from memory leaks or CPU exhaustion flaws when bombarded with malformed packets or crafted key exchange requests.

: The software suffers from an architectural state handling defect during the initial cryptographic handshake before user credentials are validated. An attacker can intentionally structure protocol messages out of order.

Router(config)# ip ssh server algorithm encryption aes256-ctr aes192-ctr aes128-ctr Router(config)# ip ssh server algorithm mac hmac-sha2-256 hmac-sha2-512 Use code with caution. Step 3: Restrict Access via Access Control Lists (ACLs)