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CVE-2023-28321

Published: 17 May 2023

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`.

Priority

Low

Cvss 3 Severity Score

5.9

Score breakdown

Status

Package Release Status
curl
Launchpad, Ubuntu, Debian
upstream
Released (8.1.0)
focal
Released (7.68.0-1ubuntu2.19)
jammy
Released (7.81.0-1ubuntu1.11)
kinetic
Released (7.85.0-1ubuntu0.6)
lunar
Released (7.88.1-8ubuntu2.1)
bionic
Released (7.58.0-2ubuntu3.24+esm1)
Available with Ubuntu Pro or Ubuntu Pro (Infra-only)
trusty
Released (7.35.0-1ubuntu2.20+esm16)
Available with Ubuntu Pro or Ubuntu Pro (Infra-only)
xenial
Released (7.47.0-1ubuntu2.19+esm9)
Available with Ubuntu Pro or Ubuntu Pro (Infra-only)
mantic
Released (7.88.1-10ubuntu1)
Patches:
upstream: https://github.com/curl/curl/commit/199f2d440d8659b42

Severity score breakdown

Parameter Value
Base score 5.9
Attack vector Network
Attack complexity High
Privileges required None
User interaction None
Scope Unchanged
Confidentiality None
Integrity impact High
Availability impact None
Vector CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N