CVE-2023-51740 affects the Skyworth CM5100 router on firmware 4.1.1.24. Its login page sends the username and password over the network in plaintext. The record rates it High at 7.5. CERT-In says to upgrade to firmware 4.1.1.25 or later, and until then to avoid logging in over networks you do not trust.
What's affected
The record and the CERT-In advisory both name one product: the Skyworth CM5100 router (a cable modem router) running firmware 4.1.1.24. The CERT-In note says the fix is to upgrade to version 4.1.1.25 or later. The record does not list a fixed version of its own, so treat the CERT-In figure as the one to verify against Skyworth or your service provider.
The record gives a CVSS score of 7.5 (High). The CVSS vector reads as follows. The attack can be reached over the network, and the complexity is low. No account is needed. No user interaction is required. Impact on confidentiality is high, on integrity none, and on availability none. The weakness class is CWE-319.
How to check if you're exposed
Log in to the device's own web interface from a trusted wired connection and read the firmware version on the status or system information page. If it says 4.1.1.24, you are on the affected build. If you manage many devices, pull the firmware field from your asset inventory or provisioning system instead of visiting each one.
This is a hardware and firmware issue, so a package scanner will not see it. If the router was supplied by an internet provider, the provider may control firmware updates, so ask them which version they have pushed.
What to do now
- Confirm the firmware version on every CM5100 you run or support.
- Upgrade to 4.1.1.25 or later, as the CERT-In advisory recommends. If the provider manages the device, ask them for the update date.
- Until the update lands, avoid logging in to the router's web interface over untrusted or shared networks, and do not reuse its password anywhere else.
- Change the administrator password after updating, since it may have crossed the network in clear text before.
Why it matters
The weakness is cleartext transmission of a credential. When a login form sends a username and password without encryption, anyone who can see the traffic between the browser and the router can read them. That includes someone on the same Wi-Fi, a compromised switch, or an upstream device on the path.
The attacker does not need to guess anything or break in first. Passive listening is enough, which is why the record scores it as needing no privileges and no user interaction. The impact is a loss of confidentiality: the stolen credentials can then be used to log in as the administrator.
Routers are easy to forget. They sit at the edge of every office and home network, and a captured admin password can let someone change DNS settings or other configuration. Treat router firmware like any other dependency with a version you track.
Quick check
Does this need an attacker on my network?
The record says the attack is network based and works by eavesdropping on traffic to the login page. In practice the attacker has to be somewhere on the path between you and the router, so shared and untrusted networks carry the most risk.
Is a fixed version available?
CERT-In names 4.1.1.25 or later. Confirm with Skyworth or your provider, because the record itself does not state a fixed version.
Sources
Last reviewed: 19 October 2026.
