Ubuntu 26.04 LTS Libidn Critical DoS Information Exposure USN-8521-1

ubuntu

July 9, 2026

Libidn could be made to crash or expose sensitive information if it received specially crafted input.

Summary

Libidn could be made to crash or expose sensitive information if it

received specially crafted input.

Software Description:

- libidn: implementation of IETF IDN specifications

Details:

It was discovered that Libidn incorrectly handled certain internationalized

domain name strings. An attacker could possibly use this issue to obtain

sensitive information or cause a denial of service.

Topics Covered

security advisory critical DoS Ubuntu information exposure libidn

Update Instructions

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

Ubuntu 26.04 LTS
  libidn12                        1.43-2ubuntu0.26.04.1

Ubuntu 24.04 LTS
  libidn12                        1.42-1ubuntu0.1

Ubuntu 22.04 LTS
  libidn12                        1.38-4ubuntu1.1

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