CVE-2026-93488: Io.netty/netty-codec-http: netty: denial of service via unbounded concurrent spdy streams

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.8% 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-770

Description

A flaw was found in Netty. SpdySessionHandler accepts an unlimited number of concurrent remote-initiated streams because localConcurrentStreams defaults to Integer.MAX_VALUE and the handler provides no API to change it. A remote peer can open a SPDY connection and send a large number of SYN_STREAM frames with FLAG_FIN=0, causing unbounded heap and direct memory allocation that can lead to JVM OutOfMemoryError and a denial of service.

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 3.33.3.SP2: all versions — fixed in 4.1.138.Final-redhat-00001
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
Red Hat Single Sign-On 7: all versions

How to fix

Upgrade to a fixed version: Red Hat Build of Apache Camel 3.33.3.SP2 4.1.138.Final-redhat-00001. Check the vendor advisory for mitigations.

References

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