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CVE-2023-28321

MEDIUMCVSS 5.9/10EPSS 1.81%

Last modified

CVE-2023-28321 is a medium-severity vulnerability rated 5.9/10 on the CVSS scale. 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. EPSS estimates a 1.81% chance of exploitation in the next 30 days.

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`.

Metrics

CVSS 3.1
5.9/10

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N

EPSS Probability
1.81%

75.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
HaxxCurl< 8.1.0
DebianDebian Linux10.0
FedoraprojectFedora37
FedoraprojectFedora38
NetappClustered Data OntapAll versions
NetappOntap Antivirus ConnectorAll versions
NetappH300s FirmwareAll versions
NetappH500s FirmwareAll versions
NetappH700s FirmwareAll versions
NetappH410s FirmwareAll versions
AppleMacos>= 11.0, < 11.7.9
AppleMacos>= 12.0, < 12.6.8
AppleMacos>= 13.0, < 13.5

References

Timeline

Published
Last Modified
Status
Modified

Frequently Asked Questions

What is CVE-2023-28321?
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`.
How severe is CVE-2023-28321?
CVE-2023-28321 has a CVSS score of 5.9/10 (MEDIUM severity). The EPSS model estimates a 1.81% probability of exploitation in the next 30 days.
How do I fix CVE-2023-28321?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST