CVE-2026-89044
Description
A flaw was found in Netty. A remote attacker could exploit improper validation of the Transfer-Encoding header by sending specially crafted HTTP requests. This vulnerability allows for HTTP request smuggling, enabling attackers to bypass security controls and potentially gain unauthorized access to sensitive information or perform actions on behalf of other users.
Statement
A flaw was found in Netty's HTTP/1 decoder where improper validation of Transfer-Encoding headers allows attackers to smuggle HTTP requests in parser-differential deployments. This affects middleware products shipping vulnerable versions (4.1.133-4.1.137) in network-facing configurations behind proxies or load balancers.
Mitigation
Update to Netty 4.1.138.Final or later. For products that cannot immediately update, ensure upstream proxies/gateways strictly validate Transfer-Encoding headers per RFC 9112 or disable HTTP/1.1 pipelining.
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).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 6.5 | N/A | 6.5 |
| 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 | Low | N/A | Low |
| Integrity Impact | Low | N/A | Low |
| Availability Impact | None | N/A | None |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
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