Advisory details:
github_osv / GHSA-6cqp-g7gg-8hr5
| Advisory ID | github_osv/GHSA-6cqp-g7gg-8hr5 |
| Aliases |
CVE-2026-56746
|
| Summary | Netty: Security Control Bypass via CORS Short-Circuit Failure ### Summary Netty's CorsHandler provides a `shortCircuit()` configuration designed to reject unauthorized cross-origin requests immediately, acting as a security control before requests reach the application. However, due to a logical operator error in the origin evaluation process, this protection can be entirely bypassed. An attacker can bypass the short-circuit mechanism by sending a request with an `Origin: null` header. This failure forwards unauthorized requests to the backend application, bypassing intended access controls. ### Details In `io.netty.handler.codec.http.cors.CorsHandler#channelRead`, the short-circuit logic relies on the configuration returned by `getForOrigin(origin)` to determine if an origin is authorized. If `getForOrigin` returns a configuration object, the short-circuit check `(!(origin == null || config != null))` is bypassed, and the request proceeds to the backend. The vulnerability is located in the `getForOrigin` method: ```java if (corsConfig.isNullOriginAllowed() || NULL_ORIGIN.equals(requestOrigin)) { return corsConfig; } ``` If an attacker sends `Origin: null`, `NULL_ORIGIN.equals(requestOrigin)` evaluates to true. The method returns the configuration object regardless of whether `isNullOriginAllowed()` was configured by the developer. The short-circuit is bypassed. ### Impact Applications relying on CorsHandler's short-circuit feature to prevent unauthorized cross-origin requests from reaching their backend logic are completely exposed. The framework fails to enforce the developer's intended access controls, allowing unauthorized requests to be processed. |
| Status | Published |
| Exploitability | 0.5 |
| Weighted Severity | 5.9 |
| Risk | 3.0 |
| Affected and Fixed Packages | Package Details |
| Introduced and Fixed Package Commit Patches | Package Commit Patches Details |
| CWE-284 | Improper Access Control |
| System | Score | Found at |
|---|---|---|
| cvssv3.1 | 6.5 | https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-6cqp-g7gg-8hr5/GHSA-6cqp-g7gg-8hr5.json |
| generic_textual | MODERATE |
No EPSS data available for this advisory.
| Patch URL | |
|---|---|
| There are no known patches. | |
| Attack Vector (AV) | Attack Complexity (AC) | Privileges Required (PR) | User Interaction (UI) | Scope (S) | Confidentiality Impact (C) | Integrity Impact (I) | Availability Impact (A) |
|---|---|---|---|---|---|---|---|
network adjacent_network local physical |
low high |
none low high |
none required |
unchanged changed |
high low none |
high low none |
high low none |
Vector: SSVCv2/E:N/A:N/T:P/P:M/B:A/M:M/D:T/2026-07-22T13:39:33Z/
Decision: Track
Source URL: https://github.com/cisagov/vulnrichment/blob/develop/2026/56xxx/CVE-2026-56746.json
Source Advisory: vulnrichment/CVE-2026-56746
[{'Exploitation': 'none'},
{'Automatable': 'no'},
{'Technical Impact': 'partial'},
{'Mission Prevalence': 'minimal'},
{'Public Well-being Impact': 'material'},
{'Mission & Well-being': 'medium'}]