# CVE-2022-43551: curl: A vulnerability exists in curl <7.87.0 HSTS check that could be bypassed to trick it to keep using HTTP

CVE-2022-43551 is fixed in 13 products on 1 platform, first by curl 7.81.0-1ubuntu1.7, released December 20, 2022. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2022-43551
- Priority: High
- CVSS: 7.5 (Medium)
- EPSS: 0.1660
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Dec 20, 2022

## Description

A vulnerability exists in curl <7.87.0 HSTS check that could be bypassed to trick it to keep using HTTP. Using its HSTS support, curl can be instructed to use HTTPS instead of using an insecure clear-text HTTP step even when HTTP is provided in the URL. However, the HSTS mechanism could be bypassed if the host name in the given URL first uses IDN characters that get replaced to ASCII counterparts as part of the IDN conversion. Like using the character UTF-8 U+3002 (IDEOGRAPHIC FULL STOP) instead of the common ASCII full stop (U+002E) `.`. Then in a subsequent request, it does not detect the HSTS state and makes a clear text transfer. Because it would store the info IDN encoded but look for it IDN decoded.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | curl Debian 12.15 (bookworm) | 7.86.0-3 | [DEBIAN-CVE-2022-43551](https://patchblox.com/security/data/fix/linux/debian-cve-2022-43551.md) | Dec 23, 2022 |
| Linux | curl Debian 13.5 (trixie) | 7.86.0-3 | [DEBIAN-CVE-2022-43551](https://patchblox.com/security/data/fix/linux/debian-cve-2022-43551.md) | Dec 23, 2022 |
| Linux | curl Debian 14 | 7.86.0-3 | [DEBIAN-CVE-2022-43551](https://patchblox.com/security/data/fix/linux/debian-cve-2022-43551.md) | Dec 23, 2022 |
| Linux | curl Ubuntu 22.04.1 LTS (jammy) | 7.81.0-1ubuntu1.7 | [curl 7.81.0-1ubuntu1.7](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-curl-7.81.0-1ubuntu1.7.md) | Dec 20, 2022 |
| Linux | curl amzn 2023 | 7.87.0-2.amzn2023.0.2 | [ALAS2023-2023-083](https://patchblox.com/security/data/fix/linux/alas2023-2023-083.md) | Feb 17, 2023 |
| Linux | curl-debuginfo amzn 2023 | 7.87.0-2.amzn2023.0.2 | [ALAS2023-2023-083](https://patchblox.com/security/data/fix/linux/alas2023-2023-083.md) | Feb 17, 2023 |
| Linux | curl-debugsource amzn 2023 | 7.87.0-2.amzn2023.0.2 | [ALAS2023-2023-083](https://patchblox.com/security/data/fix/linux/alas2023-2023-083.md) | Feb 17, 2023 |
| Linux | curl-minimal amzn 2023 | 7.87.0-2.amzn2023.0.2 | [ALAS2023-2023-083](https://patchblox.com/security/data/fix/linux/alas2023-2023-083.md) | Feb 17, 2023 |
| Linux | curl-minimal-debuginfo amzn 2023 | 7.87.0-2.amzn2023.0.2 | [ALAS2023-2023-083](https://patchblox.com/security/data/fix/linux/alas2023-2023-083.md) | Feb 17, 2023 |
| Linux | libcurl amzn 2023 | 7.87.0-2.amzn2023.0.2 | [ALAS2023-2023-083](https://patchblox.com/security/data/fix/linux/alas2023-2023-083.md) | Feb 17, 2023 |
| Linux | libcurl-debuginfo amzn 2023 | 7.87.0-2.amzn2023.0.2 | [ALAS2023-2023-083](https://patchblox.com/security/data/fix/linux/alas2023-2023-083.md) | Feb 17, 2023 |
| Linux | libcurl-devel amzn 2023 | 7.87.0-2.amzn2023.0.2 | [ALAS2023-2023-083](https://patchblox.com/security/data/fix/linux/alas2023-2023-083.md) | Feb 17, 2023 |
| Linux | libcurl-minimal amzn 2023 | 7.87.0-2.amzn2023.0.2 | [ALAS2023-2023-083](https://patchblox.com/security/data/fix/linux/alas2023-2023-083.md) | Feb 17, 2023 |
| Linux | libcurl-minimal-debuginfo amzn 2023 | 7.87.0-2.amzn2023.0.2 | [ALAS2023-2023-083](https://patchblox.com/security/data/fix/linux/alas2023-2023-083.md) | Feb 17, 2023 |
| Linux | libcurl3-gnutls Ubuntu 22.04.1 LTS (jammy) | 7.81.0-1ubuntu1.7 | [libcurl3-gnutls 7.81.0-1ubuntu1.7](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libcurl3-gnutls-7.81.0-1ubuntu1.7.md) | Dec 20, 2022 |
| Linux | libcurl3-nss Ubuntu 22.04.1 LTS (jammy) | 7.81.0-1ubuntu1.7 | [libcurl3-nss 7.81.0-1ubuntu1.7](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libcurl3-nss-7.81.0-1ubuntu1.7.md) | Dec 20, 2022 |
| Linux | libcurl4 Ubuntu 22.04.1 LTS (jammy) | 7.81.0-1ubuntu1.7 | [libcurl4 7.81.0-1ubuntu1.7](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libcurl4-7.81.0-1ubuntu1.7.md) | Dec 20, 2022 |

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