CVE-2026-93573: Io.netty/netty-codec-http: netty split transfer-encoding fields bypass final-chunked validation and enable request smuggling

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.9% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-18 · updated 2026-10-15
Weakness: CWE-444

Description

A flaw was found in Netty's HTTP/1.1 decoder. This vulnerability allows a remote attacker to bypass `Transfer-Encoding` header validation by splitting the `Transfer-Encoding` field across multiple headers, with the last field containing a non-final transfer coding like `gzip` or `deflate`. This bypass can lead to HTTP request smuggling, enabling attackers to bypass security controls, desynchronize request processing, or cause requests to be processed in an unintended context.

Affected products

Red Hat build of Keycloak 26.4: all versions
Red Hat AMQ Broker 7: all versions
Red Hat AMQ Clients: all versions
Red Hat build of Apache Camel 4 for Quarkus 3: all versions
Red Hat build of Apache Camel for Spring Boot 4: all versions
Red Hat build of Apicurio Registry 3: all versions
Red Hat Data Grid 8: all versions
Red Hat JBoss Enterprise Application Platform 8: all versions

References

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