External risk intelligence

RDK-B WebUI Heap-Based Buffer Overflow Vulnerability.

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2026-19508

The vulnerability exists in the WebUI component of RDK-B, which is a broadband gateway/router software platform. Web-based management interfaces for these types of network appliances are typically exposed to the network and are intended to be accessible for administration, making them public-facing or edge-reachable services by design in normal deployment scenarios.

Memory Corruption

Halo Surface Signal: 5 out of 5 — more likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A recent security advisory highlights a critical vulnerability in a broadband gateway software component. This issue involves a memory corruption flaw within the multipart form-data parser, which could allow an unauthenticated remote attacker to disrupt services or potentially execute unauthorized code. The primary concern is confirming if this specific technology is in use within our environment and assessing any potential exposure.

A software flaw could disrupt services or allow code execution.
It affects broadband gateway technology, often internet-facing.
Confirm relevance and exposure of affected systems.

Attack Path

How an attacker could exploit the issue

A remote attacker can send a specially crafted request to the RDK-B WebUI, bypassing authentication. This request targets the multipart form-data parser in `jst_post.c`, leading to a heap-based buffer overflow that can result in memory corruption, denial of service, and potentially arbitrary code execution.

Unauthenticated network access required.
Crafted multipart/form-data request.
Memory corruption and code execution.

Live Threat

Current exploitation, exposure, and threat context

A remote, unauthenticated attacker could trigger a heap-based buffer overflow in the multipart form-data parser. This could lead to memory corruption and denial of service. When supported by the advisory, this could also potentially allow for arbitrary code execution.

System memory corruption and denial of service.
Crafted multipart/form-data requests to the WebUI.
Potential arbitrary code execution.

Operational Fix

Recommended remediation, mitigation, and detection steps

The WebUI component of RDK-B, a broadband gateway software platform, is likely managed by infrastructure or platform teams responsible for core services, with oversight from security and vendor management teams. The initial focus should be on identifying all instances of the affected technology, assessing their network exposure and business criticality, and confirming the accountable owner before planning remediation.

Confirm affected technology deployment.
Verify network exposure and business criticality.
Coordinate with vendor and plan remediation.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

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Frequently asked questions

What is RDK-B and where is it used?

RDK-B (Reference Design Kit for Broadband) is an open-source software platform designed for broadband gateways, routers, and similar network devices. It serves as the underlying operating system and management layer that enables hardware manufacturers and service providers to deliver internet connectivity, Wi-Fi management, and device control features to end-users.

What does CVE-2026-19508 mean in simple terms?

This CVE describes a 'heap-based buffer overflow,' which is a type of memory safety error classified as CWE-119. It happens when software tries to store more data in a specific memory area than it can hold. Because this flaw exists in the component that processes multipart form-data, an attacker can send specially formatted information to overwrite adjacent memory, potentially causing the device to crash or run unauthorized commands.

How is this vulnerability triggered?

An attacker triggers this flaw by sending a specifically crafted multipart/form-data request to the WebUI component. The vulnerability is tied to the processing logic within the jst_post.c source file. Notably, because this is an unauthenticated vulnerability, the attacker does not need a valid username or password to initiate the malicious request; simply reaching the WebUI interface is sufficient.

Is my device at risk based on Halo Surface Signal?

Halo Surface Signal indicates that the RDK-B WebUI is designed as an administrative interface, making it inherently network-reachable. Because this component is often exposed to the network to facilitate management, systems running the affected version are highly likely to be accessible to remote, unauthenticated attackers, raising the urgency of evaluating your specific deployment.

What should I do if I run RDK-B software?

First, identify all devices in your environment that utilize the RDK-B platform to see if they include the affected WebUI component. Once identified, evaluate the network accessibility of these devices and check for any vendor-provided updates. Coordinate with your infrastructure or platform management teams to verify if your specific configuration is running the vulnerable version and prioritize planning for a formal fix.

References

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.