CVE-2026-42583
Description
A flaw was found in Netty, an asynchronous, event-driven network application framework. A remote attacker can exploit this vulnerability by sending a specially crafted LZ4 compressed data stream. This can cause the Lz4FrameDecoder to allocate a large amount of memory (up to 32 MB per block) before the LZ4 decompression runs, leading to excessive memory consumption and a denial of service (DoS) for the affected application.
Statement
A flaw was found in Netty's LZ4FrameDecoder. The decoder allocates a buffer based on the decompressed length from the LZ4 frame header (up to 32 MB per block) before decompression runs. A remote attacker can send a small crafted LZ4 header (as few as 22 bytes) to force excessive memory allocation, leading to a denial of service. Red Hat products that use Netty with LZ4 compression enabled are affected.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.5 | N/A | 7.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | None | N/A | None |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory); DoS: Resource Consumption (Other)
When allocating resources without limits, an attacker could prevent other systems, applications, or processes from accessing the same type of resource. It can be easy for an attacker to consume many resources by rapidly making many requests or causing larger resources to be used than is needed.
Frequently Asked Questions
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