The DIR-850L is a consumer grade wireless router released in early 2013. It is available in two hardware revisions.
The flaw was discovered on 6 August by Finland-based Tuomo Untinen who works for cyber security firm Synopsys.
Routers with hardware revision A and firmware revision 1.21B06 beta and older are vulnerable to the attack, which has the number CVE-2018-18907.
D-Link published an advisory on 6 November with links to patch that fixed the vulnerability.
Co-ordination of publication of the flaw was done by the National Cyber Security Centre, Finland.