Overview

CVE-2026-82435 is a critical vulnerability in Apache Storm, a distributed real-time computation system. The vulnerability affects Apache Storm versions prior to 3.1.0 and has a CVSS score of 9.8, indicating a high severity. This vulnerability allows an unauthenticated attacker to cause a denial-of-service (DoS) attack by sending a specially crafted frame to a worker slot port.

Understanding the Vulnerability / Threat

Root Cause Analysis

The root cause of this vulnerability is the improper placement of the Netty message decoder in the pipeline. The decoder is installed ahead of the SASL authentication handlers, allowing it to act on frames before any authentication has taken place. This design flaw enables an attacker to send a single frame that can drive a large allocation, potentially leading to a DoS attack. The vulnerability belongs to the CWE-789 category, which involves 'Uncontrolled Memory Allocation'.

Attack Surface & Vector

The attack surface of this vulnerability is the worker slot ports in Apache Storm. An attacker needs only TCP reachability to a worker port to exploit this vulnerability. The `storm.messaging.netty.authentication` configuration defaults to false, and the decoder runs before the handler that enforces it, so no credentials are required.

Exploitation Mechanics — Scenario Walkthrough

Scenario: Compromising an Apache Storm Worker 1. Initial Position: The attacker has TCP reachability to a worker slot port in Apache Storm. 2. Triggering the Flaw: The attacker crafts a specially crafted frame with a large length field, which is then sent to the worker slot port. The Netty message decoder, acting before any authentication, allocates a buffer sized from the length field carried in the frame. 3. What Breaks: The large allocation driven by the malformed frame can cause sustained worker loss or transient garbage-collection pressure, effectively leading to a denial-of-service (DoS) attack. 4. Attacker's Prize: The attacker can cause significant disruption to the Apache Storm cluster, potentially leading to a complete loss of service.

Real-World Impact

The real-world impact of this vulnerability is significant, as it allows an unauthenticated attacker to launch a DoS attack against Apache Storm clusters. This can lead to service disruptions, loss of data, and financial losses.

Detection & Defense

Immediate Mitigations

1. Upgrade to Apache Storm version 3.1.0 or later, where frames are decoded only after the handshake completes. 2. Ensure that worker slot ports are reachable only from within the cluster, as recommended by the security model. 3. Enable `storm.messaging.netty.authentication` where the deployment permits it.

Detection Strategies

1. Monitor network traffic to worker slot ports for unusual patterns or large frames. 2. Implement SIEM rules to detect and alert on potential exploitation attempts. 3. Use network signatures to identify and block malicious traffic.

Long-Term Hardening

1. Implement robust authentication and authorization mechanisms for worker slot ports. 2. Regularly update and patch Apache Storm to the latest version. 3. Conduct regular security audits and penetration testing to identify vulnerabilities.

Key Takeaways

* CVE-2026-82435 is a critical vulnerability in Apache Storm that allows for unauthenticated, remote exploitation. * The vulnerability affects Apache Storm versions prior to 3.1.0 and has a CVSS score of 9.8. * Immediate mitigations include upgrading to version 3.1.0 or later, restricting access to worker slot ports, and enabling authentication. * Long-term hardening strategies include implementing robust authentication and authorization mechanisms, regular updates and patches, and conducting regular security audits.

Sources

* National Vulnerability Database (NVD) - CVE-2026-82435