Netty 1.1 HTTP/2 response splitting

Summaryinfo

A vulnerability was found in Netty 1.1. It has been classified as critical. Impacted is an unknown function of the component HTTP2. Performing a manipulation results in response splitting. This vulnerability was named CVE-2026-93579. The attack may be initiated remotely. There is no available exploit.

Detailsinfo

A vulnerability was found in Netty 1.1. It has been classified as critical. This affects an unknown code block of the component HTTP2. The manipulation with an unknown input leads to a response splitting vulnerability. CWE is classifying the issue as CWE-113. The product receives data from an HTTP agent/component (e.g., web server, proxy, browser, etc.), but it does not neutralize or incorrectly neutralizes CR and LF characters before the data is included in outgoing HTTP headers. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

A flaw was found in Netty's HTTP/2 stack. This vulnerability allows a remote attacker to inject prohibited characters, such as NUL, Line Feed, and Carriage Return, into HTTP/2 header field values due to insufficient validation. When these values cross an HTTP/2 to HTTP/1.1 translation boundary, they can be exploited for request smuggling, header injection, or response splitting. This could lead to unauthorized access, data manipulation, or other security bypasses.

It is possible to read the advisory at access.redhat.com. This vulnerability is uniquely identified as CVE-2026-93579 since 09/18/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 09/18/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Name

• Netty

Version

• 1.1

CPE 2.3info

• 🔒

CPE 2.2info

• 🔒

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