CVE-2025-4342 is a high severity (CVSS 8.8) buffer overflow in the D-Link DIR-600L router, firmware up to 2.07B01. The formEasySetupWizard3 function mishandles the host argument. The model is no longer supported, so replace the router and limit access to its admin page in the meantime.
What's affected
D-Link DIR-600L firmware up to 2.07B01, per the record. The flaw is in the function formEasySetupWizard3, and the record names the host argument. The CVE text says the manipulation leads to a buffer overflow and that the attack may be launched remotely. Unlike some of its siblings, this record does not say the exploit has been published.
The weaknesses are tagged CWE-119 and CWE-120. The CVSS 3.1 vector is CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H, which means network reachable, low complexity, and low privileges required, so the scoring assumes some form of login. The record also says this vulnerability only affects products that are no longer supported by the maintainer, which means no fixed version is expected.
The weakness is a memory safety error. Data longer than the space set aside for it is written past the end of a buffer. The setup wizard is the part of the router interface meant for first time configuration, so it is a part of the code that many owners never look at. The record names no fixed firmware, and none is expected.
How to check if you're exposed
Find the device and read its model and firmware version from the web admin page, or from the label on the case. Compare the firmware with the affected range above.
Next, check whether the admin interface answers from outside your network. From a machine on a different network, try the router's public address on its admin port. If a login page appears, remote administration is on.
On a network you own, you can list devices that answer on common router ports.
nmap -sV -p 80,443,1900,8080 --open 192.168.0.0/24
Only scan networks you own or have permission to test.
What to do now
- Locate every unit of this model, including old ones in drawers and at remote sites.
- Plan their replacement with a supported router. The vendor does not support this model, so no patch is expected.
- Until then, turn off remote administration and make the admin page reachable only from the local network.
- Change the admin password to a long unique one.
- If the router has UPnP or similar discovery services you do not need, turn them off.
- If you cannot replace it quickly, put it behind another firewall and keep important systems on a separate network.
- Check D-Link's site for any legacy notice and record the result.
Why it matters
Routers sit between a network and the internet and run a web server that is rarely updated. A memory safety bug in the setup wizard code can crash the device or, in the worst case, let an attacker run code on it. The record does not describe the outcome in that detail. Because the model is out of support, replacing the unit is the only lasting answer.
The record does not say whether an exploit is public. It does not flag the CVE as listed in CISA's Known Exploited Vulnerabilities catalog (KEV), so there is no confirmation here of attacks in the wild. Routers past end of life are a steady target, and the right answer is to replace them.
Quick check
Will D-Link release a patch?
The record says the product is no longer supported by the maintainer, so a patch is not expected. Check D-Link's site for any legacy notice, and plan to replace the device.
Does turning off remote administration solve it?
It reduces exposure a lot, because the flaw is reached over the network. It does not remove the flaw for anyone on your local network, so replacement is still the real fix.
Sources
- Gold entry for CVE-2025-4342
- Gold entry for CWE-119
- Gold entry for CWE-120
- VulDB entry, listed in the CVE record
- D-Link website, listed in the CVE record
The reference pages are linked from the CVE record. Some block automated access, so I could not read their full text.
Last reviewed: 18 October 2026.
