Io.netty:netty codec http: Netty: Security Control Bypass via CORS Short-Circuit Failure (CVE-2026-56746)
Netty's CorsHandler includes a short-circuit feature intended to immediately reject unauthorized cross-origin requests. Due to a logical error in handling the 'Origin: null' header, this short-circuit mechanism can be bypassed, allowing unauthorized requests to reach backend applications. This bypass occurs because the method incorrectly returns a configuration object when the origin is 'null', regardless of developer settings. Applications relying on this feature for access control are exposed to unauthorized request processing.
AI Analysis
Technical Summary
The vulnerability in io.netty.handler.codec.http.cors.CorsHandler arises from a logical operator error in the short-circuit evaluation of cross-origin requests. Specifically, when the 'Origin' header is set to 'null', the method getForOrigin returns a configuration object due to the condition 'NULL_ORIGIN.equals(requestOrigin)', bypassing the intended short-circuit rejection. This flaw allows unauthorized cross-origin requests to bypass the security control and reach backend application logic, undermining the developer's access control intentions.
Potential Impact
Applications using Netty's CorsHandler short-circuit feature to block unauthorized cross-origin requests are vulnerable to bypass via 'Origin: null' headers. This results in unauthorized requests being forwarded to backend services, potentially leading to unauthorized actions or data exposure. The vulnerability does not impact confidentiality but has a high impact on integrity by allowing unauthorized request processing. Availability is not affected.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, developers should avoid relying solely on the CorsHandler short-circuit feature for access control and implement additional validation of the 'Origin' header in application logic to reject 'null' origins explicitly.
Io.netty:netty codec http: Netty: Security Control Bypass via CORS Short-Circuit Failure (CVE-2026-56746)
Description
Netty's CorsHandler includes a short-circuit feature intended to immediately reject unauthorized cross-origin requests. Due to a logical error in handling the 'Origin: null' header, this short-circuit mechanism can be bypassed, allowing unauthorized requests to reach backend applications. This bypass occurs because the method incorrectly returns a configuration object when the origin is 'null', regardless of developer settings. Applications relying on this feature for access control are exposed to unauthorized request processing.
CVSS v3.1
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability in io.netty.handler.codec.http.cors.CorsHandler arises from a logical operator error in the short-circuit evaluation of cross-origin requests. Specifically, when the 'Origin' header is set to 'null', the method getForOrigin returns a configuration object due to the condition 'NULL_ORIGIN.equals(requestOrigin)', bypassing the intended short-circuit rejection. This flaw allows unauthorized cross-origin requests to bypass the security control and reach backend application logic, undermining the developer's access control intentions.
Potential Impact
Applications using Netty's CorsHandler short-circuit feature to block unauthorized cross-origin requests are vulnerable to bypass via 'Origin: null' headers. This results in unauthorized requests being forwarded to backend services, potentially leading to unauthorized actions or data exposure. The vulnerability does not impact confidentiality but has a high impact on integrity by allowing unauthorized request processing. Availability is not affected.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, developers should avoid relying solely on the CorsHandler short-circuit feature for access control and implement additional validation of the 'Origin' header in application logic to reject 'null' origins explicitly.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-6cqp-g7gg-8hr5
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-56746"]
- Ecosystems
- ["Maven"]
- Database Specific Severity
- MODERATE
- Cvss Version
- 3.1
Threat ID: 6a6150d69c2644c7f8da0c46
Added to database: 07/22/2026, 23:23:02 UTC
Last enriched: 07/22/2026, 23:30:55 UTC
Last updated: 07/22/2026, 23:30:55 UTC
Views: 2
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