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[USN-8654-1] Netty vulnerabilities

Posted on 20 August 2026
Ubuntu Security

==========================================================================Ubuntu Security Notice USN-8654-1
August 20, 2026

netty vulnerabilities
==========================================================================
A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 24.04 LTS
- Ubuntu 22.04 LTS
- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS
- Ubuntu 16.04 LTS

Summary:

Netty could be made to crash or expose sensitive information if it
received specially crafted network traffic.

Software Description:
- netty: event-driven asynchronous network application framework

Details:

It was discovered that Netty did not properly handle malformed HTTP/2
control frames. An attacker could use this to cause a denial of service
via resource exhaustion. This issue only affects Ubuntu 18.04 LTS,
Ubuntu 20.04 LTS, Ubuntu 22.04 LTS, and Ubuntu 24.04 LTS. (CVE-2025-55163)

It was discovered that Netty did not properly validate the request URI
for line-break characters. An attacker could use this to perform CRLF
injection and request smuggling. (CVE-2025-67735)

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 24.04 LTS
libnetty-java 1:4.1.48-9ubuntu0.2

Ubuntu 22.04 LTS
libnetty-java 1:4.1.48-4+deb11u2ubuntu0.2

Ubuntu 20.04 LTS
libnetty-java 1:4.1.45-1ubuntu0.1~esm7
Available with Ubuntu Pro

Ubuntu 18.04 LTS
libnetty-java 1:4.1.7-4ubuntu0.1+esm7
Available with Ubuntu Pro

Ubuntu 16.04 LTS
libnetty-java 1:4.0.34-1ubuntu0.1~esm5
Available with Ubuntu Pro

In general, a standard system update will make all the necessary changes.

References:
https://ubuntu.com/security/notices/USN-8654-1
CVE-2025-55163, CVE-2025-67735

Package Information:
https://launchpad.net/ubuntu/+source/netty/1:4.1.48-9ubuntu0.2
https://launchpad.net/ubuntu/+source/netty/1:4.1.48-4+deb11u2ubuntu0.2

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