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VULNERABILITIES

CVE-2026-39821 Details

Description

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".

Metrics

CVSS 3.x Severity and Vector Strings:

CNA: redhat-SADPCVSS-B:8.2 HIGHVector:CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N

References to Advisories, Solutions, and Tools

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URLSource(s)Tag(s)
https://access.redhat.com/errata/RHSA-2026:23262 redhat-SADP
https://access.redhat.com/errata/RHSA-2026:23264 redhat-SADP
https://access.redhat.com/errata/RHSA-2026:26546 redhat-SADP
https://access.redhat.com/errata/RHSA-2026:26547 redhat-SADP
https://access.redhat.com/errata/RHSA-2026:30650 redhat-SADP

see all 159 references

Weakness Enumeration

CWE-IDCWE NameSource
CWE-1289Improper Validation of Unsafe Equivalence in Inputredhat-SADP
CWE-1289Improper Validation of Unsafe Equivalence in InputCISA-ADP

Affected Products

ProductVersions
golang net
< 0.55.0

CPE

  • cpe:2.3:a:golang:net:*:*:*:*:*:go:*:*

Remediation

  • No remediation found in references.

Change History

61 change records found show changes

QUICK INFO

CVE Dictionary Entry:
CVE-2026-39821
NVD Published Date:
May 22, 2026
NVD Last Modified:
Sep 17, 2026
Source:
[email protected]
CVE-2026-39821 Details - Not Deferred