CVE-2026-39821

Updated on 22 May 2026

Severity

8.2 High severity

Details

CVSS score
8.2
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N

Overview

About vulnerability

The ToASCII and ToUnicode functions incorrectly accept Punycode-encoded labels that decode to an ASCII-only label. For example, ToUnicode(“xn–example-.com”) incorrectly returns the name “example.com” rather than an error. This behavior can lead to privilege escalation in programs using the idna package. For example, a program which performs privilege checks on the ASCII hostname may reject “example.com” but permit “xn–example-.com”. If that program subsequently converts the ASCII hostname to Unicode, it will inadvertently permits access to the Unicode name “example.com”.

Details

Affected product:
AlmaLinux 9.2 ESU , TuxCare 9.6 ESU
Affected packages:
grafana @ 9.0.9 (+7 more)

Fixes