CVE-2023-28321: apple macos Improper Certificate Validation
Vulnerability summary
CVE-2023-28321 is a medium (CVSS 5.9) Improper Certificate Validation vulnerability in apple macos. EPSS estimates a 1.81% chance of exploitation in the next 30 days, higher than 78.2% of scored vulnerabilities. 1 public exploit is recorded.
Advisory lineage
Upstream 0 · Downstream 17 · Related 10Timeline
- 26-05-2023PublishedVulnerability first disclosed.
- 15-01-2025Last modifiedVulnerability information updated.
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`.
CVSS metrics
5 scores · 5 sources · 1 version- OSV · AlpineEcosystem advisory · calculated5.9MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
- OSV · UbuntuEcosystem advisory · calculated5.9MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
- OSV · DebianEcosystem advisory · calculated5.9MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
- NVDNIST5.9MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
EPSS trend
Probability
1.81%
Chance of exploitation in the next 30 days
Percentile
78%
Versus all other CVEs
30-day change
0.00 pp
From 1.81% on 18-09-2026
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
1 foundExploit Reference (hackerone.com)
Maturity: unknown
Weaknesses
CWE · root causeAffected systems
Netapp6 products
Debian2 products
- curl< 7.88.1-10
- debian_linuxEOL10.0
Alpine1 product
- curl< 8.1.0-r0
Apple1 product
- macos≥ 11.0, < 11.7.9 | ≥ 12.0, < 12.6.8 | ≥ 13.0, < 13.5
Chainguard1 product
- libcurl4All versions (No fix recorded)
Fedoraproject1 product
- fedoraEOL37 | 38
Haxx1 product
- curl< 8.1.0
Ubuntu1 product
- curl< 7.35.0-1ubuntu2.20+esm16 | < 7.47.0-1ubuntu2.19+esm9 | < 7.58.0-2ubuntu3.24+esm1 | < 7.68.0-1ubuntu2.19 | < 7.81.0-1ubuntu1.11
Wolfi1 product
- libcurl4All versions (No fix recorded)
9 vendors · 15 products
References
20 links- lists.fedoraproject.org/archives/…Vendor Advisory
- lists.fedoraproject.org/archives/…Vendor Advisory
- security.netapp.com/advisory/ntap-20230609-0009/Third Party Advisory
- support.apple.com/kb/HT213843Third Party Advisory
- support.apple.com/kb/HT213844Third Party Advisory
- support.apple.com/kb/HT213845Third Party Advisory
