Eclipse Vert.x Redis Parser Flaw Triggers Massive Memory Allocations, Crashing Event Loops in DoS Attack
A parser flaw in Eclipse Vert.x allows malicious Redis servers to trigger massive memory allocations that crash application event loops and deny service.
Key points
- CVE-2026-102465 affects Eclipse Vert.x versions 4.0.0 through 5.2.0.
- The flaw allows attackers to declare extremely large array lengths in RESP responses.
- Successful exploitation causes OutOfMemoryError crashes that deny service to all connections.
Eclipse Vert.x applications connecting to Redis servers face a denial-of-service risk due to a parser flaw in the Redis client component. The issue stems from how the client handles Response Protocol messages, specifically regarding array length declarations sent by the server. According to the National Vulnerability Database record for CVE-2026-102465, the parser pre-allocates memory arrays based on lengths declared by the server without enforcing any upper bound on size.
The risk
The vulnerability carries a CVSS score of 8.2, which the National Vulnerability Database rates as high severity. An attacker who controls or compromises a Redis server, or who can perform a man-in-the-middle attack, can send a crafted response containing an extremely large array, push, or attribute length declaration. The Vert.x Redis client attempts to allocate a heap segment matching this declared size. This massive allocation request typically triggers an OutOfMemoryError within the Java Virtual Machine hosting the application.
Who is exposed
The flaw impacts the Vert.x Redis client component within the Eclipse Vert.x framework. Affected software includes Eclipse Vert.x versions 4.0.0 through 4.5.34, versions 5.0.0 through 5.0.12, versions 5.1.0 through 5.1.9, and version 5.2.0. Any organization running these specific versions of the framework and utilizing the Redis client module is potentially exposed to this denial-of-service vector.
Cost and compliance
The source material does not provide details regarding financial costs, regulatory compliance impacts, or specific industry sectors affected by this vulnerability. The National Vulnerability Database record focuses exclusively on the technical mechanics of the flaw, the affected version ranges, and the severity rating. No information about confirmed exploitation in the wild, victim counts, or remediation costs is included in the provided source material.
What to watch
Security teams should immediately inventory all applications running Eclipse Vert.x to identify instances using the affected version ranges. Organizations should verify whether their Vert.x applications communicate with Redis instances that could be influenced by malicious actors or compromised infrastructure. Monitoring for sudden application crashes or memory exhaustion events in Vert.x event loops is critical for early detection of this attack vector.
Signals worth monitoring
Teams usually observe sudden spikes in heap memory usage followed by immediate process termination. Application logs will typically record OutOfMemoryError exceptions originating from the Vert.x Redis client parser. Check whether network monitoring tools flag unusually large response payloads from Redis servers to client applications. Defenders should look for patterns where multiple connections to the same event loop fail simultaneously. Review server-side access logs to identify unauthorized configuration changes that might enable crafted responses.
What to do and how to stay safe: Eclipse Vert.x
- Audit your software bill of materials to identify all instances of Eclipse Vert.x versions 4.0.0 through 5.2.0.
- Implement network segmentation to ensure Vert.x clients only communicate with trusted, authenticated Redis servers.
- Configure application-level timeouts and memory limits to mitigate the impact of unexpected large allocations.
- Monitor application logs for OutOfMemoryError exceptions and sudden drops in active connection counts.
Step-by-step guide: Vulnerability Prioritization: Fix What Actually Matters First
General security guidance from the SecOps Signal newsroom. It is not confirmed advice from the organisations named in this story.
Frequently asked questions
Which versions of Eclipse Vert.x are affected by CVE-2026-102465?
Versions 4.0.0 through 4.5.34, 5.0.0 through 5.0.12, 5.1.0 through 5.1.9, and 5.2.0 are affected.
What is the severity rating for this vulnerability?
The National Vulnerability Database rates the severity as high with a CVSS score of 8.2.
How does the attacker exploit this flaw?
The attacker sends a crafted RESP response declaring an extremely large array length, causing the client to exhaust heap memory.
