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MEDIUM

CVE-2023-34462

CVSS v3

6.5

MEDIUM

EPSS Score

2.5 %

exploit probability, as of 2026-10-19

CISA KEV

No

known exploited

Exploitation

—

SSVC status

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Affected and fixed versions

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • io.netty:netty-handlerMavenall versions · fixed in 4.1.94.Final

Vendor advisories

  • CVE-2023-34462 Red Hat Product Security116 products fixed · 24 known affected

    netty: SniHandler 16MB allocation leads to OOM

    netty as a component of A-MQ Clients 2 · org.jboss.windup-windup-parent.src as a component of Migration Toolkit for Applications 6 · org.jboss.windup-windup-parent.src as a component of Migration Toolkit for Runtimes

  • RHSA-2024:0148 Red Hat Product Security1 product fixed

    Red Hat Security Advisory: Red Hat Integration Camel K 1.10.5 release and security update

  • RHSA-2023:7700 Red Hat Product Security1 product fixed

    Red Hat Security Advisory: Red Hat build of Quarkus 2.13.9 release and security update

  • RHSA-2023:7697 Red Hat Product Security1 product fixed

    Red Hat Security Advisory: AMQ Clients 2023.Q4

  • RHSA-2023:7669 Red Hat Product Security12 products fixed

    Red Hat Security Advisory: Red Hat build of Cryostat 2.4.0: new RHEL 8 container images

  • RHSA-2023:7653 Red Hat Product Security1 product fixed

    Red Hat Security Advisory: Service Registry (container images) release and security update [2.5.4 GA]

8 more advisories

Full record on NVD

Description

Netty is an asynchronous event-driven network application framework for rapid development of maintainable high performance protocol servers & clients. The `SniHandler` can allocate up to 16MB of heap for each channel during the TLS handshake. When the handler or the channel does not have an idle timeout, it can be used to make a TCP server using the `SniHandler` to allocate 16MB of heap. The `SniHandler` class is a handler that waits for the TLS handshake to configure a `SslHandler` according to the indicated server name by the `ClientHello` record. For this matter it allocates a `ByteBuf` using the value defined in the `ClientHello` record. Normally the value of the packet should be smaller than the handshake packet but there are not checks done here and the way the code is written, it is possible to craft a packet that makes the `SslClientHelloHandler`. This vulnerability has been fixed in version 4.1.94.Final.

Technical details

Published
2023-06-22

Frequently asked questions

What is CVE-2023-34462?

Netty is an asynchronous event-driven network application framework for rapid development of maintainable high performance protocol servers & clients. The `SniHandler` can allocate up to 16MB of heap for each channel during the TLS handshake. When the handler or the channel does not have an idle timeout, it can be used to make a TCP server using the `SniHandler` to allocate 16MB of heap. The `SniHandler` class is a handler that waits for the TLS handshake to configure a `SslHandler` according to the indicated server name by the `ClientHello` record. For this matter it allocates a `ByteBuf` using the value defined in the `ClientHello` record. Normally the value of the packet should be smaller than the handshake packet but there are not checks done here and the way the code is written, it is possible to craft a packet that makes the `SslClientHelloHandler`. This vulnerability has been fixed in version 4.1.94.Final.

Is CVE-2023-34462 actively exploited?

Active exploitation of CVE-2023-34462 has not been confirmed. Its EPSS score was 2.5% on 2026-10-19, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2023-34462?

CVE-2023-34462 has a CVSS v3 base score of 6.5 (MEDIUM severity).

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