CVE-2026-42584
Description
A flaw was found in Netty, an asynchronous, event-driven network application framework. A remote attacker could exploit this vulnerability by sending a specific sequence of HTTP responses (103, followed by a 200 with a GET body, then another 200 for a HEAD request) when the client pipelines GET then HEAD requests. This can cause the HttpClientCodec to incorrectly pair responses, leading to subsequent HTTP responses being parsed from the wrong offset. This issue may result in information disclosure or other data integrity problems due to misinterpretation of network traffic.
Statement
Important: A flaw in Netty's HttpClientCodec allows a remote attacker to cause data confusion. By sending a specially crafted sequence of HTTP responses, an attacker can cause subsequent HTTP responses to be parsed incorrectly, potentially leading to information disclosure or data integrity issues in applications utilizing Netty for HTTP client operations. This vulnerability affects various Red Hat products that bundle Netty, including Red Hat AMQ, Enterprise Application Platform, Red Hat Build of Quarkus, and Red Hat Build of Keycloak.
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 | 7.3 | 9.1 | 7.3 |
| Attack Vector | Network | Network | Network |
| Attack Complexity | Low | Low | Low |
| Privileges Required | None | None | None |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | Low | None | Low |
| Integrity Impact | Low | High | Low |
| Availability Impact | Low | High | Low |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
Understanding the Weakness (CWE)
Integrity,Non-Repudiation,Access Control
Technical Impact: Unexpected State; Hide Activities; Bypass Protection Mechanism
An attacker could create HTTP messages to exploit a number of weaknesses including 1) the message can trick the web server to associate a URL with another URL's webpage and caching the contents of the webpage (web cache poisoning attack), 2) the message can be structured to bypass the firewall protection mechanisms and gain unauthorized access to a web application, and 3) the message can invoke a script or a page that returns client credentials (similar to a Cross Site Scripting attack).
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