TOTOLINK - Authentication Bypass (CVE-2019-19825)

CVE-2019-19825 is a critical vulnerability in certain TOTOLINK Realtek SDK-based routers that allows attackers to bypass CAPTCHA protections by retrieving the CAPTCHA text via a crafted POST request. This flaw enables remote attackers to automate login attempts and, once valid credentials are obtained, perform unauthorized router actions through HTTP requests with Basic Authentication. The vulnerability exposes affected devices to risks such as unauthorized configuration changes and potential network compromise.

CrowdSec has been tracking this vulnerability and its exploits since 10th of December 2025.

CrowdSec network data shows that most actors exploiting CVE-2019-19825 rely on broad, untargeted scans with minimal filtering. The activity is largely automated and opportunistic in nature. CrowdSec network telemetry also shows that exploitation of CVE-2019-19825 has significantly declined over the past week. Attack volumes are well below the long-term average, suggesting attackers are rapidly losing interest. The vulnerability appears to be falling out of active use across most threat landscapes.

Attackers exploit the CAPTCHA bypass by sending a POST request with the payload {"topicurl":"setting/getSanvas"} to the /boafrm/formLogin endpoint on TOTOLINK and Realtek-based routers, allowing them to retrieve the CAPTCHA value and facilitate unauthorized access.