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Severity by source

Vendor (redhat) PRIMARY
7.5 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
vuln.today AI
7.5 HIGH

Unauthenticated remote flood of a reachable SPDY endpoint (AV:N/AC:L/PR:N/UI:N) with availability-only impact via OOM (A:H); the SPDY-enabled requirement is a deployment gate, not attack complexity.

3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Primary rating from Vendor (redhat).

CVSS VectorVendor: redhat

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

3
Metadata Corrected
Sep 18, 2026 - 12:40 vuln.today
tag: Netty added
Analysis Generated
Sep 18, 2026 - 12:15 vuln.today
CVE Published
Sep 18, 2026 - 11:47 cve.org
HIGH 7.5

DescriptionCVE.org

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.

AnalysisAI

Unbounded remote-initiated stream creation in Netty's SpdySessionHandler allows an unauthenticated, network-positioned attacker to exhaust JVM heap and direct memory on any application that exposes a SPDY endpoint, producing OutOfMemoryError and a denial of service. The handler initializes localConcurrentStreams to Integer.MAX_VALUE and provides no API to change it, so no supported configuration knob reduces the exposure once SPDY is reachable; Netty 4.1.x before 4.1.138.Final and 4.2.x before 4.2.18.Final are affected, along with the Red Hat products that bundle those versions (AMQ Broker and AMQ Clients, Camel for Quarkus 3 and for Spring Boot 4, Keycloak, Quarkus, Debezium, Apicurio Registry, Data Grid, Fuse, JBoss EAP 7/8, and RH-SSO 7). …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

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Delivery
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Exploit
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Execution
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Vulnerability AssessmentAI

Exploitation Requires that the target application has explicitly configured Netty's SPDY support (SpdySessionHandler / netty-codec-http SPDY pipeline) and exposed that endpoint to attackers - SPDY is not enabled by default and is a deprecated protocol, which is the primary limiting factor. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment The CVSS vector (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H, base 7.5) describes an unauthenticated, network-reachable, low-complexity attack with pure availability impact and no confidentiality or integrity loss - an availability-only denial-of-service, consistent with CWE-770 (uncontrolled resource consumption). … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario Full exploit scenario with step-by-step reproduction available after sign-in.
Remediation Vendor-released patch: upgrade io.netty:netty-codec-http to 4.1.138.Final or 4.2.18.Final (the releases that contain the SPDY unbounded-resource fix), and for Red Hat subscribers apply the errata referenced from https://access.redhat.com/security/cve/CVE-2026-93488 and https://bugzilla.redhat.com/show_bug.cgi?id=2536887, which cover AMQ Broker/Clients, Camel for Quarkus 3 and Spring Boot 4, Apicurio Registry 3, Debezium 3, Keycloak, Quarkus, Data Grid 8, Fuse 7, JBoss EAP 7/8, and RH-SSO 7; because the handler offers no API to lower localConcurrentStreams, there is no Netty-level configuration workaround, so the primary compensating control is to remove the SPDY codec from the channel pipeline entirely (do not install SpdySessionHandler or reference netty-codec-http SPDY classes) - the trade-off is that any residual SPDY clients lose protocol support, which is generally acceptable given SPDY is deprecated and superseded by HTTP/2. … Detailed patch versions, workarounds, and compensating controls in full report.

Recommended ActionAI

Within 24 hours, inventory every Java service in the estate - including Keycloak, AMQ Broker and Clients, Quarkus, Camel for Quarkus 3 and Spring Boot 4, Debezium, Apicurio Registry, Data Grid, Fuse, JBoss EAP 7/8 and RH-SSO 7 - that embeds Netty and determine whether any Netty pipeline registers a SPDY handler; SPDY is deprecated and off by default, so the fastest risk reduction is to remove or disable the SPDY handler and any SPDY listener from application configurations, or block the corresponding ports at the network edge. …

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EUVD-2026-82887 vulnerability details – vuln.today

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