Description
An improper certificate validation vulnerability exists in curl <v8.1.0 in the way it supports matching of wildcard patterns when listed as "Subject Alternative Name" in TLS server certificates. curl can be built to use its own name matching function for TLS rather than one provided by a TLS library. This private wildcard matching function would match IDN (International Domain Name) hosts incorrectly and could as a result accept patterns that otherwise should mismatch. IDN hostnames are converted to puny code before used for certificate checks. Puny coded names always start with `xn--` and should not be allowed to pattern match, but the wildcard check in curl could still check for `x*`, which would match even though the IDN name most likely contained nothing even resembling an `x`.
Published: 2023-05-26
Score: 5.9 Medium
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

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Tracking

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Advisories
Source ID Title
Debian DLA Debian DLA DLA-3613-1 curl security update
EUVD EUVD EUVD-2023-32028 An improper certificate validation vulnerability exists in curl <v8.1.0 in the way it supports matching of wildcard patterns when listed as "Subject Alternative Name" in TLS server certificates. curl can be built to use its own name matching function for TLS rather than one provided by a TLS library. This private wildcard matching function would match IDN (International Domain Name) hosts incorrectly and could as a result accept patterns that otherwise should mismatch. IDN hostnames are converted to puny code before used for certificate checks. Puny coded names always start with `xn--` and should not be allowed to pattern match, but the wildcard check in curl could still check for `x*`, which would match even though the IDN name most likely contained nothing even resembling an `x`.
Ubuntu USN Ubuntu USN USN-6237-1 curl vulnerabilities
Ubuntu USN Ubuntu USN USN-6237-3 curl vulnerabilities
History

Wed, 16 Jul 2025 13:45:00 +0000

Type Values Removed Values Added
Metrics epss

{'score': 0.00285}

epss

{'score': 0.00297}


Wed, 15 Jan 2025 16:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Subscriptions

Apple Macos
Debian Debian Linux
Fedoraproject Fedora
Haxx Curl
Netapp Clustered Data Ontap H300s H300s Firmware H410s H410s Firmware H500s H500s Firmware H700s H700s Firmware Ontap Antivirus Connector
Redhat Enterprise Linux Jboss Core Services Rhel Eus
cve-icon MITRE

Status: PUBLISHED

Assigner: hackerone

Published:

Updated: 2025-01-15T15:54:33.745Z

Reserved: 2023-03-14T00:00:00.000Z

Link: CVE-2023-28321

cve-icon Vulnrichment

Updated: 2024-08-02T12:38:24.939Z

cve-icon NVD

Status : Modified

Published: 2023-05-26T21:15:16.020

Modified: 2025-01-15T16:15:26.203

Link: CVE-2023-28321

cve-icon Redhat

Severity : Moderate

Publid Date: 2023-05-17T00:00:00Z

Links: CVE-2023-28321 - Bugzilla

cve-icon OpenCVE Enrichment

No data.

Weaknesses