CVE-2026-93569: netty HTTP Request/Response Smuggling

Vulnerability summary

CVE-2026-93569 is a high (CVSS 8.2) HTTP Request/Response Smuggling vulnerability in netty. EPSS estimates a 2.19% chance of exploitation in the next 30 days, higher than 82.1% of scored vulnerabilities.

Timeline

1. 18-09-2026
   PublishedVulnerability first disclosed.
2. 19-10-2026
   Last modifiedVulnerability information updated.

Description

A flaw was found in Netty. A remote unauthenticated attacker can exploit a vulnerability in Netty's HTTP/1 to HTTP/2 conversion process. When an HTTP/1 request includes both an absolute-form request-target and a conflicting Host header, Netty incorrectly prioritizes the Host header for the HTTP/2 :authority field, discarding the original request-target authority. This inconsistency can allow an attacker to bypass security controls in Netty-based proxies or gateways, potentially leading to unauthorized access, cache poisoning, or misrouting of requests.

• CWE-444Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination.