CVE-2026-19507 in RDK-B WebUI
Summary
by MITRE • 08/19/2026
Uncontrolled resource consumption in `check.jst` in RDK-B WebUI `rdkb-2025q4-kirkstone.04.10.26` allows a remote unauthenticated attacker to cause denial of service via excessively large password values.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 08/19/2026
The vulnerability identified within the RDK-B WebUI, specifically affecting the check.jst component in version rdkb-2025q4-kirkstone.04.10.26, represents a critical flaw rooted in uncontrolled resource consumption. This issue arises from insufficient validation and sanitization of user-supplied input prior to its processing by the server-side logic. The core technical deficiency lies in the failure to enforce strict length limits or complexity constraints on password fields during authentication attempts. When an attacker submits a password value that is excessively large, the system allocates memory buffers without checking for potential overflow conditions or imposing reasonable boundaries on data size. This lack of input validation allows malicious actors to trigger disproportionate resource allocation relative to the computational effort required by legitimate users.
From a technical perspective, this flaw aligns with Common Weakness Enumeration category CWE-400, which describes uncontrolled resource consumption. The vulnerability is further characterized as CWE-20, improper input validation, because the application fails to adequately verify that incoming data conforms to expected formats and sizes before processing. In many web frameworks, including those used in RDK-B environments, string handling operations such as concatenation or hashing can become computationally expensive when dealing with massive inputs. If the underlying cryptographic libraries or parsing routines are not optimized for large payloads, they may enter infinite loops or consume excessive CPU cycles while attempting to process the oversized data structure. This behavior effectively starves system resources of their capacity to handle legitimate requests, leading to a degradation in service availability.
The operational impact of this vulnerability is primarily centered on denial of service conditions. A remote unauthenticated attacker can exploit this flaw by repeatedly sending HTTP POST or GET requests containing extremely large password strings to the authentication endpoint. Each request consumes significant memory and processing power on the target device. Since no rate limiting or input size restrictions are in place, an automated attack script can rapidly exhaust available system resources. This results in the WebUI becoming unresponsive, preventing legitimate administrators from accessing management interfaces or performing critical network configuration tasks. In embedded systems like those running RDK-B, which often operate with constrained hardware resources compared to standard servers, such resource exhaustion can lead to complete device freezes requiring a hard reboot to restore functionality.
This attack vector is consistent with techniques documented in the MITRE ATT&CK framework under T1498, Network Denial of Service, specifically reflecting methods that involve flooding or overwhelming target systems through excessive requests. The unauthenticated nature of this exploit makes it particularly dangerous as it does not require prior access credentials to initiate an attack. Attackers can leverage publicly accessible web interfaces on IoT devices and set-top boxes running RDK-B software to disrupt network operations without needing any form of authentication, thereby lowering the barrier for entry significantly.
Mitigation strategies must focus on implementing robust input validation mechanisms at both the application layer and infrastructure level. Developers should enforce strict maximum length constraints on all password fields within check.jst and associated backend handlers. Implementing server-side checks to reject payloads exceeding a defined byte limit before any processing occurs is essential. Additionally, integrating rate limiting controls can help mitigate the impact of automated flooding attacks by throttling requests from single IP addresses that exhibit suspicious behavior patterns. Upgrading to patched versions of RDK-B where these input validation flaws have been addressed remains the most effective long-term solution for organizations relying on this software stack.