Vulnerability in Curl

CVE-2026-8458

libcurl might in some circumstances reuse the wrong connection when asked to do Negotiate-authenticated ones, even when they are set to use different 'services'. libcurl features a pool of recent connections so that subsequent requests can reuse an existing connection to avoid overhead. When reusing a connection a range of criteria must be met. Due to a logical error in the code, a request that was issued by an application could wrongfully reuse an existing connection to the same server that was authenticated using different services.

EPSS: 0.003 (23.9th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N.

Affected products

References

Frequently asked questions

What is CVE-2026-8458?
CVE-2026-8458 is a medium-severity vulnerability in Curl, classified under CWE-488 EXPOSURE OF DATA ELEMENT TO WRONG SESSION. CVSS score: 6.5/10. Published 2026-07-03.
How severe is CVE-2026-8458?
Medium severity. CVSS v3 base score is 6.5 out of 10.