Detections
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Golang: stdlib: security update to 1.25.13stdlib: security update to 1.26.6stdlib: security update to 1.27.0-rc.3

high Tenable Cloud Security Plugin ID 445963

Description

There are packages installed that are affected by a vulnerability referenced in the following CVE:

 - 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". (CVE-2026-39821)

Solution

Update the stdlib library and its related packages to version 1.25.13 or later.

See Also

https://pkg.go.dev/vuln/GO-2026-5026

Plugin Details

Severity: High

ID: 445963

Version: Revision 1.1

Type: Local

Family: Golang

Published: 8/14/2026

Updated: 8/14/2026

Risk Information

VPR

Risk Factor: Medium

Score: 4.8

Percentile: 57.82

CVSS v2

Risk Factor: High

Base Score: 9.4

Temporal Score: 7

Vector: CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:N

CVSS Score Source: CVE-2026-39821

CVSS v3

Risk Factor: High

Base Score: 8.2

Temporal Score: 7.1

Vector: CVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

Exploit Ease: No known exploits are available

Patch Publication Date: 5/22/2026

Vulnerability Publication Date: 5/12/2026

Reference Information

CVE: CVE-2026-39821