CVE-2026-126348

Addressable display_uri can show misleading hosts with invalid Punycode A-labels

Published Nov 12, 2026 CVSS 3.1 · 4.3 Medium EPSS n/a KEV · Not listed
Description
Addressable is an alternative implementation to the URI implementation that is part of Ruby's standard library. From 2.0.0 until 2.9.1, the pure-Ruby Addressable::IDNA.to_unicode implementation decodes invalid Punycode A-labels instead of returning them unchanged. Labels that decode to ASCII text or fail to convert back to the same A-label can therefore make Addressable::URI#display_uri show a trusted-looking host while host, normalized_host, and the connection target retain the attacker-controlled encoded host. A trusted-name comparison using Addressable::IDNA.to_unicode output can also treat two different hosts as the same without displaying the URI. The native libidn implementation, to_ascii, and normalized_host are unaffected. This issue is fixed in version 2.9.1.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-9crm-g4mf-wc5j Addressable display_uri can show misleading hosts with invalid Punycode A-labels
History
Type Values Removed Values Added
Description Addressable is an alternative implementation to the URI implementation that is part of Ruby's standard library. From 2.0.0 until 2.9.1, the pure-Ruby Addressable::IDNA.to_unicode implementation decodes invalid Punycode A-labels instead of returning them unchanged. Labels that decode to ASCII text or fail to convert back to the same A-label can therefore make Addressable::URI#display_uri show a trusted-looking host while host, normalized_host, and the connection target retain the attacker-controlled encoded host. A trusted-name comparison using Addressable::IDNA.to_unicode output can also treat two different hosts as the same without displaying the URI. The native libidn implementation, to_ascii, and normalized_host are unaffected. This issue is fixed in version 2.9.1.
Title Addressable display_uri can show misleading hosts with invalid Punycode A-labels
Weaknesses CWE-1007
CWE-20
References
Metrics cvssV3_1

{'score': 4.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N'}

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Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Nov 13, 2026, 12:34 AM
Reserved
Nov 10, 2026, 9:12 PM
Status
Received
Published
Nov 12, 2026, 10:19 PM
Modified
Nov 13, 2026, 2:18 AM