==========================================================================
Ubuntu Security Notice USN-8233-1
May 05, 2026

nghttp2 vulnerability
==========================================================================

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

- Ubuntu 25.10
- Ubuntu 24.04 LTS
- Ubuntu 22.04 LTS
- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS
- Ubuntu 16.04 LTS

Summary:

nghttp2 could be made to crash if it received specially crafted
network traffic.

Software Description:
- nghttp2: HTTP/2 C Library and tools

Details:

Andrew MacPherson discovered that nghttp2 did not properly validate
internal state when the session termination API was called. A remote
attacker could possibly use this issue to cause nghttp2 to crash, resulting
in a denial of service.

Update instructions:

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

Ubuntu 25.10
  libnghttp2-14                   1.64.0-1.1ubuntu1.1
  nghttp2                         1.64.0-1.1ubuntu1.1

Ubuntu 24.04 LTS
  libnghttp2-14                   1.59.0-1ubuntu0.3
  nghttp2                         1.59.0-1ubuntu0.3

Ubuntu 22.04 LTS
  libnghttp2-14                   1.43.0-1ubuntu0.3
  nghttp2                         1.43.0-1ubuntu0.3

Ubuntu 20.04 LTS
  libnghttp2-14                   1.40.0-1ubuntu0.3+esm1
                                  Available with Ubuntu Pro
  nghttp2                         1.40.0-1ubuntu0.3+esm1
                                  Available with Ubuntu Pro

Ubuntu 18.04 LTS
  libnghttp2-14                   1.30.0-1ubuntu1+esm3
                                  Available with Ubuntu Pro
  nghttp2                         1.30.0-1ubuntu1+esm3
                                  Available with Ubuntu Pro

Ubuntu 16.04 LTS
  libnghttp2-14                   1.7.1-1ubuntu0.1~esm3
                                  Available with Ubuntu Pro
  nghttp2                         1.7.1-1ubuntu0.1~esm3
                                  Available with Ubuntu Pro

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

References:
  https://ubuntu.com/security/notices/USN-8233-1
  CVE-2026-27135

Package Information:
  https://launchpad.net/ubuntu/+source/nghttp2/1.64.0-1.1ubuntu1.1
  https://launchpad.net/ubuntu/+source/nghttp2/1.59.0-1ubuntu0.3
  https://launchpad.net/ubuntu/+source/nghttp2/1.43.0-1ubuntu0.3