External risk intelligence

Apache Storm Netty Decoder Unauthenticated Large Allocation Vulnerability

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2026-82435

The vulnerable component is a worker slot port in a cluster environment. These ports are typically intended for internal cluster communication rather than direct public internet exposure, and the provided mitigation explicitly recommends restricting reachability to within the cluster.

Halo Surface Signal: 2 out of 5 — less likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A security flaw has been identified in a message processing component within certain cluster environments that could allow unauthenticated access to trigger large memory allocations. While the direct impact on system stability from a single event is unmeasured, the potential exists for significant resource consumption. The primary concern is confirming if this specific technology is deployed and accessible within our infrastructure.

Unauthenticated component may consume excess memory.
Potential for resource exhaustion requires confirmation.
Confirm if this component is in use and exposed.

Attack Path

How an attacker could exploit the issue

An attacker can target a worker slot port that is reachable over the network. The vulnerable component is a message decoder that processes data before authentication, allowing an unauthenticated sender to send a specially crafted frame. This can lead to a large memory allocation, potentially impacting the worker's availability.

Network access to a worker port.
Sending a crafted network frame.
Potential denial-of-service impact.

Live Threat

Current exploitation, exposure, and threat context

A critical vulnerability exists where an unauthenticated peer can send a specially crafted network frame to a worker slot port before authentication. This could lead to large memory allocations, potentially impacting service availability. The exact effect on worker stability, such as sustained loss versus transient performance issues, requires further testing against specific configurations.

Worker memory buffers at risk.
Large allocations from unauthenticated frames.
Potential for service disruption.

Operational Fix

Recommended remediation, mitigation, and detection steps

In a clustered environment, platform or infrastructure teams are likely responsible for securing worker slot ports. The first practical step is to confirm network reachability to these ports, assess their business criticality, and identify the accountable owner to plan remediation.

Platform/Infrastructure teams own remediation.
Verify worker port reachability and criticality.
Plan remediation based on exposure.

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 Apache Storm and its worker slot ports?

Apache Storm is a distributed real-time computation system used to process large streams of data. It relies on worker nodes to execute tasks, which communicate with each other over the network via worker slot ports. These ports handle the continuous flow of data frames required for the cluster to perform its distributed processing duties.

What does CWE-789 mean for CVE-2026-82435?

CWE-789 refers to uncontrolled memory allocation. In this vulnerability, the Netty message decoder reads a length field from an incoming data frame and uses it to reserve memory before verifying who sent the message. Because this happens prior to authentication, an attacker can manipulate that length value to force the software to allocate an excessively large amount of RAM.

How does an attacker trigger this memory issue?

An attacker triggers this by sending a specially crafted network frame directly to a worker slot port. Crucially, the vulnerability exists because the decoder processes this frame before any authentication handshake occurs. Internal cluster traffic that is already authenticated or processed after a completed handshake does not trigger this specific memory allocation flaw.

Is my system at risk if it is not internet-facing?

According to Halo Surface Signal, these worker slot ports are typically intended for internal cluster communication rather than direct exposure to the public internet. While the vulnerability requires network reachability, systems that are properly segmented and restricted to internal-only access carry significantly lower risk than those inadvertently exposed to wider networks.

What is the recommended first step for this CVE?

Begin by confirming if your infrastructure uses Apache Storm and verifying which network segments can reach the worker slot ports. If you cannot upgrade to version 3.1.0 immediately, ensure these ports are strictly isolated within your internal cluster environment and enable the message authentication setting if your specific deployment architecture allows it.

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.