D-Link DWR-X1820 routers exposed to weak default password attacks
D-Link DWR-X1820 routers use weak default passwords derived from IMEI numbers, allowing attackers who know the IMEI to easily predict credentials.
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What to check
- Applies to
- The 1 CVE named below. Whether you run an affected version is not assessed: check the versions the source lists.
- Exploitation
- No exploitation in the wild and no public exploit is recorded for the CVEs named.
CERT Polska coordinated disclosure of CVE-2026-4377, a vulnerability affecting D-Link DWR-X1820 routers. The flaw stems from the use of weak default passwords that are algorithmically generated from the device's IMEI number. Critically, the router does not enforce a password change upon initial configuration, leaving devices vulnerable to credential prediction attacks.
An attacker who obtains or observes a device's IMEI number can use knowledge of the password generation algorithm to derive the default administrative password. This could enable unauthorized access to router configuration, potentially allowing network interception, traffic manipulation, or use of the device as a pivot point for further attacks. The vulnerability was addressed in firmware version 1.00B16CP.
The issue was responsibly disclosed by security researcher Bartłomiej Włodarski through CERT Polska's coordinated vulnerability disclosure process. Organizations and individuals using affected D-Link DWR-X1820 routers should update to version 1.00B16CP or later and manually change default passwords if they have not already done so.
Mentioned in this report
Source reporting: https://cert.pl/en/posts/2026/05/CVE-2026-4377
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