==========================================================================
Ubuntu Security Notice USN-8416-1
June 09, 2026

golang-golang-x-net-dev vulnerability
==========================================================================

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

- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS

Summary:

Go Networking could allow unintended access to network services.

Software Description:
- golang-golang-x-net-dev: Supplementary Go networking development files

Details:

It was discovered that Go Networking incorrectly handled certain
Punycode-encoded labels in the idna package. An attacker could possibly use
this issue to bypass hostname-based access restrictions.

Update instructions:

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

Ubuntu 20.04 LTS
  golang-go.net-dev               1:0.0+git20190811.74dc4d7+dfsg-1ubuntu0.1~esm3
                                  Available with Ubuntu Pro
  golang-golang-x-net-dev         1:0.0+git20190811.74dc4d7+dfsg-1ubuntu0.1~esm3
                                  Available with Ubuntu Pro

Ubuntu 18.04 LTS
  golang-go.net-dev               1:0.0+git20170629.c81e7f2+dfsg-2ubuntu0.1~esm3
                                  Available with Ubuntu Pro
  golang-golang-x-net-dev         1:0.0+git20170629.c81e7f2+dfsg-2ubuntu0.1~esm3
                                  Available with Ubuntu Pro

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

References:
  https://ubuntu.com/security/notices/USN-8416-1
  CVE-2026-39821