# CVE-2023-28321: curl: An improper certificate validation vulnerability exists in curl <v8.1.0 inthe way it supports matching of wildcard pa...

CVE-2023-28321 is fixed in 15 products on 1 platform, first by curl 7.58.0-2ubuntu3.24+esm1, released May 16, 2023. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2023-28321
- Priority: Routine
- CVSS: 5.9 (Low)
- EPSS: 0.0181
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: May 16, 2023

## Description

An improper certificate validation vulnerability exists in curl <v8.1.0 inthe way it supports matching of wildcard patterns when listed as "SubjectAlternative Name" in TLS server certificates. curl can be built to use itsown name matching function for TLS rather than one provided by a TLSlibrary. This private wildcard matching function would match IDN(International Domain Name) hosts incorrectly and could as a result acceptpatterns that otherwise should mismatch. IDN hostnames are converted topuny code before used for certificate checks. Puny coded names always startwith `xn--` and should not be allowed to pattern match, but the wildcardcheck in curl could still check for `x*`, which would match even though theIDN name most likely contained nothing even resembling an `x`.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | curl Debian 12.15 (bookworm) | 7.88.1-10 | [DEBIAN-CVE-2023-28321](https://patchblox.com/security/data/fix/linux/debian-cve-2023-28321.md) | May 26, 2023 |
| Linux | curl Debian 13.5 (trixie) | 7.88.1-10 | [DEBIAN-CVE-2023-28321](https://patchblox.com/security/data/fix/linux/debian-cve-2023-28321.md) | May 26, 2023 |
| Linux | curl Debian 14 | 7.88.1-10 | [DEBIAN-CVE-2023-28321](https://patchblox.com/security/data/fix/linux/debian-cve-2023-28321.md) | May 26, 2023 |
| Linux | curl RHEL 8 | 0:7.61.1-30.el8_8.3 | [RHSA-2023:4523](https://patchblox.com/security/data/fix/linux/rhsa-2023-4523.md) | Aug 8, 2023 |
| Linux | curl RHEL 9 | 0:7.76.1-23.el9_2.2 | [RHSA-2023:4354](https://patchblox.com/security/data/fix/linux/rhsa-2023-4354.md) | Aug 1, 2023 |
| Linux | curl Ubuntu 18.04.6 LTS (bionic) | 7.58.0-2ubuntu3.24+esm1 | [curl 7.58.0-2ubuntu3.24+esm1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-curl-7.58.0-2ubuntu3.24-esm1.md) | May 16, 2023 |
| Linux | curl Ubuntu 20.04 LTS (focal) | 7.68.0-1ubuntu2.19 | [curl 7.68.0-1ubuntu2.19](https://patchblox.com/security/data/fix/linux/ubuntu-focal-curl-7.68.0-1ubuntu2.19.md) | May 16, 2023 |
| Linux | curl Ubuntu 22.04.1 LTS (jammy) | 7.81.0-1ubuntu1.11 | [curl 7.81.0-1ubuntu1.11](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-curl-7.81.0-1ubuntu1.11.md) | May 16, 2023 |
| Linux | curl Ubuntu 24.10 (oracular) | 7.88.1-10ubuntu1 | [curl 7.88.1-10ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-oracular-curl-7.88.1-10ubuntu1.md) | Jan 16, 2026 |
| Linux | curl Ubuntu 25.04 (plucky) | 7.88.1-10ubuntu1 | [curl 7.88.1-10ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-plucky-curl-7.88.1-10ubuntu1.md) | Jan 16, 2026 |
| Linux | curl almalinux 8 | 7.61.1-30.el8_8.3 | [ALSA-2023:4523](https://patchblox.com/security/data/fix/linux/alsa-2023-4523.md) | Aug 8, 2023 |
| Linux | curl almalinux 9 | 7.76.1-23.el9_2.2 | [ALSA-2023:4354](https://patchblox.com/security/data/fix/linux/alsa-2023-4354.md) | Aug 1, 2023 |
| Linux | curl amzn 2023 | 8.0.1-1.amzn2023.0.1 | [ALAS2023-2023-270](https://patchblox.com/security/data/fix/linux/alas2023-2023-270.md) | Jul 19, 2023 |
| Linux | curl ol 8 | 0:7.61.1-30.el8_8.3 | [ELSA-2023-4523](https://patchblox.com/security/data/fix/linux/elsa-2023-4523.md) | Aug 10, 2023 |
| Linux | curl ol 9 | 0:7.76.1-23.el9_2.2 | [ELSA-2023-4354](https://patchblox.com/security/data/fix/linux/elsa-2023-4354.md) | Aug 2, 2023 |
| Linux | curl rocky 8 | 0:7.61.1-30.el8_8.3 | [RLSA-2023:4523](https://patchblox.com/security/data/fix/linux/rlsa-2023-4523.md) | Oct 6, 2023 |
| Linux | curl-debuginfo amzn 2023 | 8.0.1-1.amzn2023.0.1 | [ALAS2023-2023-270](https://patchblox.com/security/data/fix/linux/alas2023-2023-270.md) | Jul 19, 2023 |
| Linux | curl-debugsource amzn 2023 | 8.0.1-1.amzn2023.0.1 | [ALAS2023-2023-270](https://patchblox.com/security/data/fix/linux/alas2023-2023-270.md) | Jul 19, 2023 |
| Linux | curl-minimal RHEL 9 | 0:7.76.1-23.el9_2.2 | [RHSA-2023:4354](https://patchblox.com/security/data/fix/linux/rhsa-2023-4354.md) | Aug 1, 2023 |
| Linux | curl-minimal almalinux 9 | 7.76.1-23.el9_2.2 | [ALSA-2023:4354](https://patchblox.com/security/data/fix/linux/alsa-2023-4354.md) | Aug 1, 2023 |
| Linux | curl-minimal amzn 2023 | 8.0.1-1.amzn2023.0.1 | [ALAS2023-2023-270](https://patchblox.com/security/data/fix/linux/alas2023-2023-270.md) | Jul 19, 2023 |
| Linux | curl-minimal ol 9 | 0:7.76.1-23.el9_2.2 | [ELSA-2023-4354](https://patchblox.com/security/data/fix/linux/elsa-2023-4354.md) | Aug 2, 2023 |
| Linux | curl-minimal-debuginfo amzn 2023 | 8.0.1-1.amzn2023.0.1 | [ALAS2023-2023-270](https://patchblox.com/security/data/fix/linux/alas2023-2023-270.md) | Jul 19, 2023 |
| Linux | libcurl RHEL 8 | 0:7.61.1-30.el8_8.3 | [RHSA-2023:4523](https://patchblox.com/security/data/fix/linux/rhsa-2023-4523.md) | Aug 8, 2023 |
| Linux | libcurl RHEL 9 | 0:7.76.1-23.el9_2.2 | [RHSA-2023:4354](https://patchblox.com/security/data/fix/linux/rhsa-2023-4354.md) | Aug 1, 2023 |
| Linux | libcurl almalinux 8 | 7.61.1-30.el8_8.3 | [ALSA-2023:4523](https://patchblox.com/security/data/fix/linux/alsa-2023-4523.md) | Aug 8, 2023 |
| Linux | libcurl almalinux 9 | 7.76.1-23.el9_2.2 | [ALSA-2023:4354](https://patchblox.com/security/data/fix/linux/alsa-2023-4354.md) | Aug 1, 2023 |
| Linux | libcurl amzn 2023 | 8.0.1-1.amzn2023.0.1 | [ALAS2023-2023-270](https://patchblox.com/security/data/fix/linux/alas2023-2023-270.md) | Jul 19, 2023 |
| Linux | libcurl ol 8 | 0:7.61.1-30.el8_8.3 | [ELSA-2023-4523](https://patchblox.com/security/data/fix/linux/elsa-2023-4523.md) | Aug 10, 2023 |
| Linux | libcurl ol 9 | 0:7.76.1-23.el9_2.2 | [ELSA-2023-4354](https://patchblox.com/security/data/fix/linux/elsa-2023-4354.md) | Aug 2, 2023 |
| Linux | libcurl-debuginfo amzn 2023 | 8.0.1-1.amzn2023.0.1 | [ALAS2023-2023-270](https://patchblox.com/security/data/fix/linux/alas2023-2023-270.md) | Jul 19, 2023 |
| Linux | libcurl-devel RHEL 8 | 0:7.61.1-30.el8_8.3 | [RHSA-2023:4523](https://patchblox.com/security/data/fix/linux/rhsa-2023-4523.md) | Aug 8, 2023 |
| Linux | libcurl-devel RHEL 9 | 0:7.76.1-23.el9_2.2 | [RHSA-2023:4354](https://patchblox.com/security/data/fix/linux/rhsa-2023-4354.md) | Aug 1, 2023 |
| Linux | libcurl-devel almalinux 8 | 7.61.1-30.el8_8.3 | [ALSA-2023:4523](https://patchblox.com/security/data/fix/linux/alsa-2023-4523.md) | Aug 8, 2023 |
| Linux | libcurl-devel almalinux 9 | 7.76.1-23.el9_2.2 | [ALSA-2023:4354](https://patchblox.com/security/data/fix/linux/alsa-2023-4354.md) | Aug 1, 2023 |
| Linux | libcurl-devel amzn 2023 | 8.0.1-1.amzn2023.0.1 | [ALAS2023-2023-270](https://patchblox.com/security/data/fix/linux/alas2023-2023-270.md) | Jul 19, 2023 |
| Linux | libcurl-devel ol 8 | 0:7.61.1-30.el8_8.3 | [ELSA-2023-4523](https://patchblox.com/security/data/fix/linux/elsa-2023-4523.md) | Aug 10, 2023 |
| Linux | libcurl-devel ol 9 | 0:7.76.1-23.el9_2.2 | [ELSA-2023-4354](https://patchblox.com/security/data/fix/linux/elsa-2023-4354.md) | Aug 2, 2023 |
| Linux | libcurl-minimal RHEL 8 | 0:7.61.1-30.el8_8.3 | [RHSA-2023:4523](https://patchblox.com/security/data/fix/linux/rhsa-2023-4523.md) | Aug 8, 2023 |
| Linux | libcurl-minimal RHEL 9 | 0:7.76.1-23.el9_2.2 | [RHSA-2023:4354](https://patchblox.com/security/data/fix/linux/rhsa-2023-4354.md) | Aug 1, 2023 |
| Linux | libcurl-minimal almalinux 8 | 7.61.1-30.el8_8.3 | [ALSA-2023:4523](https://patchblox.com/security/data/fix/linux/alsa-2023-4523.md) | Aug 8, 2023 |
| Linux | libcurl-minimal almalinux 9 | 7.76.1-23.el9_2.2 | [ALSA-2023:4354](https://patchblox.com/security/data/fix/linux/alsa-2023-4354.md) | Aug 1, 2023 |
| Linux | libcurl-minimal amzn 2023 | 8.0.1-1.amzn2023.0.1 | [ALAS2023-2023-270](https://patchblox.com/security/data/fix/linux/alas2023-2023-270.md) | Jul 19, 2023 |
| Linux | libcurl-minimal ol 8 | 0:7.61.1-30.el8_8.3 | [ELSA-2023-4523](https://patchblox.com/security/data/fix/linux/elsa-2023-4523.md) | Aug 10, 2023 |
| Linux | libcurl-minimal ol 9 | 0:7.76.1-23.el9_2.2 | [ELSA-2023-4354](https://patchblox.com/security/data/fix/linux/elsa-2023-4354.md) | Aug 2, 2023 |
| Linux | libcurl-minimal-debuginfo amzn 2023 | 8.0.1-1.amzn2023.0.1 | [ALAS2023-2023-270](https://patchblox.com/security/data/fix/linux/alas2023-2023-270.md) | Jul 19, 2023 |
| Linux | libcurl3-gnutls Ubuntu 18.04.6 LTS (bionic) | 7.58.0-2ubuntu3.24+esm1 | [libcurl3-gnutls 7.58.0-2ubuntu3.24+esm1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-libcurl3-gnutls-7.58.0-2ubuntu3.24-esm1.md) | May 16, 2023 |
| Linux | libcurl3-gnutls Ubuntu 20.04 LTS (focal) | 7.68.0-1ubuntu2.19 | [libcurl3-gnutls 7.68.0-1ubuntu2.19](https://patchblox.com/security/data/fix/linux/ubuntu-focal-libcurl3-gnutls-7.68.0-1ubuntu2.19.md) | May 16, 2023 |
| Linux | libcurl3-gnutls Ubuntu 22.04.1 LTS (jammy) | 7.81.0-1ubuntu1.11 | [libcurl3-gnutls 7.81.0-1ubuntu1.11](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libcurl3-gnutls-7.81.0-1ubuntu1.11.md) | May 16, 2023 |
| Linux | libcurl3-nss Ubuntu 18.04.6 LTS (bionic) | 7.58.0-2ubuntu3.24+esm1 | [libcurl3-nss 7.58.0-2ubuntu3.24+esm1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-libcurl3-nss-7.58.0-2ubuntu3.24-esm1.md) | May 16, 2023 |
| Linux | libcurl3-nss Ubuntu 20.04 LTS (focal) | 7.68.0-1ubuntu2.19 | [libcurl3-nss 7.68.0-1ubuntu2.19](https://patchblox.com/security/data/fix/linux/ubuntu-focal-libcurl3-nss-7.68.0-1ubuntu2.19.md) | May 16, 2023 |
| Linux | libcurl3-nss Ubuntu 22.04.1 LTS (jammy) | 7.81.0-1ubuntu1.11 | [libcurl3-nss 7.81.0-1ubuntu1.11](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libcurl3-nss-7.81.0-1ubuntu1.11.md) | May 16, 2023 |
| Linux | libcurl3t64-gnutls Ubuntu 24.10 (oracular) | 7.88.1-10ubuntu1 | [libcurl3t64-gnutls 7.88.1-10ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-oracular-libcurl3t64-gnutls-7.88.1-10ubuntu1.md) | Jan 16, 2026 |
| Linux | libcurl3t64-gnutls Ubuntu 25.04 (plucky) | 7.88.1-10ubuntu1 | [libcurl3t64-gnutls 7.88.1-10ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-plucky-libcurl3t64-gnutls-7.88.1-10ubuntu1.md) | Jan 16, 2026 |
| Linux | libcurl4 Ubuntu 18.04.6 LTS (bionic) | 7.58.0-2ubuntu3.24+esm1 | [libcurl4 7.58.0-2ubuntu3.24+esm1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-libcurl4-7.58.0-2ubuntu3.24-esm1.md) | May 16, 2023 |
| Linux | libcurl4 Ubuntu 20.04 LTS (focal) | 7.68.0-1ubuntu2.19 | [libcurl4 7.68.0-1ubuntu2.19](https://patchblox.com/security/data/fix/linux/ubuntu-focal-libcurl4-7.68.0-1ubuntu2.19.md) | May 16, 2023 |
| Linux | libcurl4 Ubuntu 22.04.1 LTS (jammy) | 7.81.0-1ubuntu1.11 | [libcurl4 7.81.0-1ubuntu1.11](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libcurl4-7.81.0-1ubuntu1.11.md) | May 16, 2023 |
| Linux | libcurl4t64 Ubuntu 24.10 (oracular) | 7.88.1-10ubuntu1 | [libcurl4t64 7.88.1-10ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-oracular-libcurl4t64-7.88.1-10ubuntu1.md) | Jan 16, 2026 |
| Linux | libcurl4t64 Ubuntu 25.04 (plucky) | 7.88.1-10ubuntu1 | [libcurl4t64 7.88.1-10ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-plucky-libcurl4t64-7.88.1-10ubuntu1.md) | Jan 16, 2026 |

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