CVE-2023-23915: A cleartext transmission of sensitive information vulnerability exists in curl <v7.88.0 that could cause HSTS functionality to behave incorrectly when multiple URLs are requested in parallel. 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. This HSTS mechanism would however surprisingly fail when multiple transfers are done in parallel as the HSTS cache file gets overwritten by the most recentlycompleted transfer. A later HTTP-only transfer to the earlier host name would then *not* get upgraded properly to HSTS.
Overview
- Severity
- Medium (CVSS 6.5)
- CVSS Vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
- Exploit Status
- Not Exploited
- Patch Tuesday
- 2023-Feb
- Released
- 2023-02-24
- Last Updated
- 2026-02-18
- EPSS Score
- 0.86% (percentile: 54.8%)
FAQ
Is Azure Linux the only Microsoft product that includes this open-source library and is therefore potentially affected by this vulnerability?
One of the main benefits to our customers who choose to use the Azure Linux distro is the commitment to keep it up to date with the most recent and most secure versions of the open source libraries with which the distro is composed. Microsoft is committed to transparency in this work which is why we began publishing CSAF/VEX in October 2025. See this blog post for more information. If impact to additional products is identified, we will update the CVE to reflect this.
Affected Products (15)
Other
- 18295-17084
- 19686-17084
- 19671-17084
- 17941-16820
- 17950-16820
- 17951-16820
- 17952-16820
- 17953-16823
- 17954-16823
- 17955-16823
- 17959-16823
- 17878-17084
- 17957-17084
- 17879-17084
- 19668-17086
Revision History
- 2023-02-24: Information published.
- 2024-06-30: Information published.
- 2026-02-18: Information published.