CVE-2023-28321

What it is

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`.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of data tampering.

Exploit odds

1.8% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2023-05-26 21:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-10-23 23:10 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 1.8% in the next 30 days (EPSS).
• Severity: 5.9 MEDIUM (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2023-05-26 21:15 UTC

Last modified

2026-10-23 23:10 UTC

Exploit probability

1.8% · EPSS, next 30 days

Weakness

CWE-295 · Improper certificate validation

Record status

Modified

Affected

• Haxx Curl < 8.1.0
• Debian Linux 10.0
• Fedoraproject Fedora 37
• Fedoraproject Fedora 38
• Netapp Clustered Data Ontap
• Netapp Ontap Antivirus Connector
• Netapp h300s Firmware
• Netapp h500s Firmware

Attack profile CVSS 3.1 · 5.9

Attack vector

Network

Complexity

High

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

High

Availability

None

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2023-28321.md and follow it. Check whether this project is affected by CVE-2023-28321. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

Copy as ticket · More options · Status badge