CVE-2026-56746
Description
A flaw was found in Netty, a network application framework. A remote attacker can bypass security controls in the CorsHandler component by sending a specially crafted request with a null origin header. This bypasses the intended access restrictions, allowing unauthorized requests to reach the backend application. This could lead to a compromise of data integrity by allowing unauthorized actions.
Statement
Red Hat ships Netty's netty-codec-http component in multiple products. The CorsHandler shortCircuit() feature, when enabled, is intended to reject unauthorized cross-origin requests before they reach the application. Due to a logical operator error in origin validation, requests with a null Origin header bypass this protection entirely. Upgrade to Netty 4.1.136.Final or 4.2.16.Final to resolve this issue.
Mitigation
If CORS short-circuit functionality is not required, disable the shortCircuit() configuration in the CorsHandler. Alternatively, implement application-level origin validation to reject requests with null Origin headers. A web application firewall (WAF) can also be configured to block requests with null or missing Origin headers.
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 | 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 | Required |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | High | N/A | High |
| Availability Impact | None | N/A | None |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
Understanding the Weakness (CWE)
Confidentiality,Access Control,Availability,Other
Technical Impact: Bypass Protection Mechanism; Gain Privileges or Assume Identity; Varies by Context
Attackers can bypass the security decision to access whatever is being protected. The consequences will depend on the associated functionality, but they can range from granting additional privileges to untrusted users to bypassing important security checks. Ultimately, this weakness may lead to exposure or modification of sensitive data, system crash, or execution of arbitrary code.
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