Design/Logic Flaw

An issue was discovered on D-Link DIR-890L with firmware 1.21B02beta01 and earlier, DIR-885L/R with firmware 1.21B03beta01 and earlier, and DIR-895L/R with firmware 1.21B04beta04 and earlier devices (all hardware revisions). Due to the predictability of the /docs/captcha_(number).jpeg URI, being local to the network, but unauthenticated to the administrator’s panel, an attacker can disclose the CAPTCHAs used by the access point and can elect to load the CAPTCHA of their choosing, leading to unauthorized login attempts to the access point.