: Support for diffie-hellman-group1-sha1 or diffie-hellman-group-exchange-sha1 .
Because the Cisco-1.25 software variant handles legacy cryptographic configurations on older hardware, scanners frequently alert on man-in-the-middle (MitM) vulnerabilities like the (CVE-2023-48795).
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Security audits often list this as a "medium" or "low" risk because of Information Disclosure
To mitigate and remediate this vulnerability, Cisco has released patches and workarounds. The recommended solutions are: The recommended solutions are: More recent research into
More recent research into Cisco products (as of 2025) has highlighted vulnerabilities within the Erlang/OTP SSH server implementation used by some Cisco components, which can sometimes be identified by similar SSH banners during scans. 3. Threat Landscape: Why Should You Care?
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. When a vulnerability scanner flags SSH-2
: If an attacker knew a valid local username configured for RSA authentication, a flaw in how the SSH engine parsed the key allowed entry without validating ownership of the matching private key.
: The module mishandles invalid or malformed RSA keys during the validation phase.
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: An attacker can establish a standard SSH session and transmit a carefully crafted sequence of malformed packets. Instead of dropping the corrupted packets, the engine triggers an unexpected internal error, causing the entire device to reload or crash, leading to a network-wide Denial of Service. 3. Cryptographic Downgrade and Terrapin Attacks