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CVE-2023-28321

5.9 · MEDIUM

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.

Published May 26, 2023CWE-295EPSS 1.81%

Overview

CVE-2023-28321 is a medium-severity vulnerability. It was published on May 26, 2023 and has a CVSS 3.1 base score of 5.9 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 5.9, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical 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`.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refseclists.org/fulldisclosure/2023/Jul/47Refseclists.org/fulldisclosure/2023/Jul/48Refseclists.org/fulldisclosure/2023/Jul/52Refhackerone.com/reports/1950627Reflists.debian.org/debian-lts-announce/2023/10/msg00016.htmlReflists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/F4I75RDGX5ULSSCBE5BF3P5I5SFO7ULQ/Reflists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/Z2LIWHWKOVH24COGGBCVOWDXXIUPKOMK/Refsecurity.gentoo.org/glsa/202310-12Refsecurity.netapp.com/advisory/ntap-20230609-0009/Refsupport.apple.com/kb/HT213843

How CyberStrike helps

Frequently asked questions

What is CVE-2023-28321?

CVE-2023-28321 is a medium-severity vulnerability. It was published on May 26, 2023 and has a CVSS 3.1 base score of 5.9 (MEDIUM).

How severe is CVE-2023-28321?

This vulnerability has a CVSS 3.1 base score of 5.9, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2023-28321?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2023-28321?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2023-28321 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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