The ADB (formerly Pirelli Broadband Solutions) P.DGA4001N router with firmware PDG_TEF_SP_4.06L.6, and possibly other routers, uses "1236790" and the MAC address to generate the WPA key.
https://exchange.xforce.ibmcloud.com/vulnerabilities/99682
http://www.exploit-db.com/exploits/35721
Source: Mitre, NVD
Published: 2020-01-14
Updated: 2020-01-24
Base Score: 5
Vector: CVSS2#AV:N/AC:L/Au:N/C:N/I:P/A:N
Severity: Medium
Base Score: 5.3
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
EPSS: 0.00108