CVE-2023-23915

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.9% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2023-02-23 · updated 2026-10-24
Weakness: CWE-319

Description

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.

Affected products

curl: from 7.77.0 before 7.88.0 — fixed in 7.88.0
Active IQ Unified Manager for VMware vSphere, Linux, and Microsoft Windows: all versions
Clustered Data ONTAP: 9.0
NetApp H300S Firmware: all versions
NetApp H410S Firmware: all versions
NetApp H500S Firmware: all versions
NetApp H700S Firmware: all versions
Splunk Universal Forwarder: from 8.2.0 before 8.2.12; from 9.0.0 before 9.0.6; 9.1.0 — fixed in 8.2.12, 9.0.6

How to fix

Upgrade to a fixed version: curl 7.88.0; Splunk Universal Forwarder 8.2.12, 9.0.6. Check the vendor advisory for mitigations.

References

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