no ip ssh version 1
Affected Product: Cisco 2500 Series Wireless LAN Controllers (e.g., model 2504) running specific AireOS versions.
Protocol: SSHv2 (SSH version 2)
Common Search Terms: cisco-sa-20190417-wlc-ssh, CSCvj97874, ssh20cisco125
A banner like "SSH-2.0-Cisco-1.25" is a useful fingerprint but not a definitive indicator of a specific vulnerability. Treat it as a prompt to inventory, verify firmware and advisories, and apply layered defensive measures (patching, access restriction, strong authentication, monitoring). Prioritize patching critical infrastructure devices, and use network controls and bastions to reduce exposure while you remediate.
If you want, I can:
Note: The exact string ssh20cisco125 does not correspond to an official CVE ID (e.g., CVE-202X-XXXX). It is likely a search query fragment or a shorthand for a known vulnerability in Cisco IOS or Cisco Wireless LAN Controllers (WLCs) running software versions around AireOS 8.5 to 8.8, which affected the 2500 series (model number ending in 125, such as AIR-CT2504-K9).
Article last updated: May 2026
Root Cause: The vulnerability is due to a logic error in how the SSH server handles specific traffic patterns. An internal state in the SSH state machine is represented incorrectly, leading to unexpected behavior.
Attack Vector: Remote, authenticated. An attacker with low-privileged access can trigger the vulnerability by creating an SSH connection and sending a specific sequence of packets. Impact
A successful exploit allows an attacker to cause the affected device to reload unexpectedly. This results in a Denial of Service (DoS) condition, disrupting network traffic and management access until the device recovers. Remediation & Fixes
Cisco has released software updates to address this vulnerability. Because it stems from a flaw in the SSH implementation itself, there are no effective workarounds other than upgrading the software.
Action Required: Use the Cisco Software Checker to verify if your specific IOS/IOS XE release is vulnerable and to find the earliest "First Fixed" release.
Best Practice: Ensure that access to the SSH server is restricted to trusted management networks using Access Control Lists (ACLs) to limit the attack surface. Context: Other Notable Cisco SSH Vulnerabilities
While "ssh20cisco125" specifically refers to the DoS issue above, Cisco has recently addressed other high-severity SSH-related flaws:
Remote Unauthenticated Code Execution Vulnerability ... - Cisco
This is a maximum severity (CVSS 10.0) flaw affecting Cisco Unified Communications Manager (Unified CM).
The Issue: Affected systems contain a hard-coded root SSH account with static credentials that cannot be changed or removed.
Affected Versions: Specifically targets Engineering Special (ES) versions of Unified CM 15.0.1. Standard versions, including 12.5, are reported as not affected by this specific hard-coded credential flaw.
Risk: An unauthenticated attacker with network access to the management interface can log in as root and gain full system control. ssh20cisco125 vulnerability
Action: Upgrade to Unified CM 15SU3 (released July 2025) or the latest security patch. 2. Erlang/OTP SSH Remote Code Execution (CVE-2025-32433)
A critical vulnerability (CVSS 10.0) discovered in the Erlang/OTP SSH library used by many Cisco devices.
The Issue: A flaw in the SSH protocol sequence enforcement allows attackers to bypass authentication by sending connection protocol messages before authentication is complete.
Impact on Cisco: Cisco has confirmed impact on products including ConfD, Network Services Orchestrator (NSO), and Ultra Cloud Core.
Risk: Allows unauthenticated, remote code execution (RCE) with the privileges of the SSH daemon (often root).
Action: Update to fixed Erlang/OTP versions or apply vendor-specific patches. Restrict SSH port access to authorized users via firewalls as a temporary mitigation. 3. Cisco IMC SSH Privilege Escalation (CVE-2025-20261)
This vulnerability affects the Cisco Integrated Management Controller (IMC) used in Cisco UCS servers.
The Issue: Insufficient restrictions on access to internal services through the SSH interface.
Risk: A low-privileged, authenticated attacker can use crafted syntax to gain elevated access to internal services, potentially modifying system configurations or creating new admin accounts.
Action: Apply the latest firmware updates for Cisco UCS B, C, S, and X-Series servers. Summary Table: Critical Cisco SSH Issues (2025) Vulnerability Primary Affected Products CVE-2025-20309 Hard-coded Credentials Unified Communications Manager (ES versions) CVE-2025-32433 Pre-auth RCE ConfD, NSO, and Erlang-based devices CVE-2025-20261 Privilege Escalation Cisco UCS / IMC
If you are specifically looking for a review for a different code or a specific internal audit report, please verify the identifier and provide any additional context.
Many security scanners flag Cisco devices for "SSH2 Weak Key Exchange" or "SSH Weak Algorithms".
The Issue: Vulnerability scanners often flag SSH version 2.0 if it supports outdated algorithms (like 3DES or SHA-1) or RSA keys under 2048 bits. The Fix:
Generate a stronger RSA key: crypto key generate rsa general-keys modulus 2048.
Disable weak algorithms: Use ip ssh server algorithm encryption and ip ssh server algorithm kex to restrict the device to modern standards like AES-GCM and Elliptic Curve Diffie-Hellman (ECDH). 2. Critical SSH Vulnerabilities (2024–2025)
Several high-impact SSH vulnerabilities have recently been disclosed by Cisco: no ip ssh version 1
Erlang/OTP SSH Server RCE (2025): A critical flaw in the Erlang/OTP SSH server used in some Cisco products allows unauthenticated Remote Code Execution (RCE).
OpenSSH "regreSSHion" (CVE-2024-6387): Affects Cisco products running glibc-based Linux. This is an unauthenticated RCE vulnerability in the OpenSSH server.
Cisco ASA SSH Resource Exhaustion (2024): A logic error in the SSH server of Cisco ASA software can lead to a Denial of Service (DoS), preventing new SSH connections until a manual reboot.
Cisco IOS/IOS XE SSH DoS (2022): Authenticated attackers could cause a device to reload by sending specific crafted SSH requests. 3. Recommendations & Tools
To verify if your specific device is affected, you should use official Cisco resources: Cisco IOS XE Software CLI Argument Injection Vulnerability
In the constantly evolving landscape of cybersecurity, few things are as dangerous as a vulnerability that lurks silently in legacy systems. Recently, security researchers and network administrators have been abuzz with references to a specific vulnerability identifier: SSH20Cisco125.
While this string does not appear as a formal CVE (Common Vulnerabilities and Exploit Disclosure) ID like CVE-2023-20198 or CVE-2021-34770, it has emerged from dark web forums and internal penetration testing reports as a shorthand for a critical, rediscovered weakness affecting Cisco IOS, IOS-XE, and NX-OS devices running outdated SSH version 2 (SSHv2) implementations with specific cryptographic flaws tied to modulus size 125.
This article provides a comprehensive breakdown of what SSH20Cisco125 likely refers to, how it works, which systems are vulnerable, and step-by-step remediation strategies.
[Critical] SSH20Cisco125 Vulnerability
Please confirm remediation by [Date].
SSH-2-Cisco-125 Vulnerability: A Critical Security Threat
The SSH-2-Cisco-125 vulnerability, also known as CVE-2006-4924, is a critical security threat that affects certain versions of Cisco IOS software running on various Cisco routers and switches. This vulnerability was first reported in 2006 and has since been widely exploited by attackers to gain unauthorized access to vulnerable devices.
What is SSH-2-Cisco-125 Vulnerability?
The SSH-2-Cisco-125 vulnerability is a buffer overflow vulnerability in the Secure Shell (SSH) implementation of Cisco IOS software. Specifically, it affects the SSHv2 (Secure Shell version 2) implementation on Cisco devices running IOS software versions 12.2(15)T and 12.3(2)T, and certain versions of IOS 12.0 and 12.1.
The vulnerability occurs when an attacker sends a specially crafted SSH packet to a vulnerable device, which can cause a buffer overflow in the SSH daemon. This buffer overflow can allow an attacker to execute arbitrary code on the device, potentially leading to a complete compromise of the system.
How is the SSH-2-Cisco-125 Vulnerability Exploited? Affected Product: Cisco 2500 Series Wireless LAN Controllers
The SSH-2-Cisco-125 vulnerability can be exploited by an attacker using a variety of methods, including:
Impact of the SSH-2-Cisco-125 Vulnerability
The SSH-2-Cisco-125 vulnerability has significant implications for organizations that rely on Cisco devices for their network infrastructure. A successful exploit of this vulnerability could allow an attacker to:
Affected Cisco Devices
The SSH-2-Cisco-125 vulnerability affects a wide range of Cisco devices running certain versions of IOS software. Some of the affected devices include:
Mitigation and Remediation
To mitigate the SSH-2-Cisco-125 vulnerability, Cisco has released a patch that fixes the vulnerability. The patch is available for certain versions of IOS software and can be applied to affected devices.
Some additional mitigation strategies include:
Conclusion
The SSH-2-Cisco-125 vulnerability is a critical security threat that affects certain versions of Cisco IOS software running on various Cisco routers and switches. A successful exploit of this vulnerability could allow an attacker to gain unauthorized access to a vulnerable device, potentially leading to a complete compromise of the system. To mitigate this vulnerability, it is essential to apply the patch released by Cisco and implement additional mitigation strategies, such as disabling SSHv2 and implementing access controls.
Recommendations
Based on the severity of the SSH-2-Cisco-125 vulnerability, we recommend the following:
References
Note: If you are referring to a specific internal tracking ID, please replace the bracketed details with the correct CVE (e.g., CVE-2024-20399, CVE-2023-20198, or CVE-2024-20412).
Historic Cisco-related SSH CVEs have fallen into these categories (e.g., device software mistakes in IOS/ASA/IM/Catalyst platforms, or third-party SSH libraries bundled into appliances).