CVE-2026-39821 Affecting go-toolset:rhel8/go-toolset package, versions <0:1.26.5-1.module_el8.10.0+4223+bd807c2e


Severity

Recommended
high

Based on AlmaLinux security rating.

Threat Intelligence

EPSS
0.66% (48th percentile)

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  • Snyk IDSNYK-ALMALINUX8-GOTOOLSET-17976992
  • published15 Jul 2026
  • disclosed9 Jul 2026

Introduced: 9 Jul 2026

CVE-2026-39821  (opens in a new tab)

How to fix?

Upgrade AlmaLinux:8 go-toolset:rhel8/go-toolset to version 0:1.26.5-1.module_el8.10.0+4223+bd807c2e or higher.
This issue was patched in ALSA-2026:38995.

NVD Description

Note: Versions mentioned in the description apply only to the upstream go-toolset:rhel8/go-toolset package and not the go-toolset:rhel8/go-toolset package as distributed by AlmaLinux. See How to fix? for AlmaLinux:8 relevant fixed versions and status.

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".

References

CVSS Base Scores

version 3.1