CVE-2026-8458: Haxx Curl

Medium severity, CVSS 6.5. EPSS: 0.4% chance of exploitation in the next 30 days.

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.

Affected products

• Haxx Curl: from 7.46.0, before 8.20.0 (fixed in 8.20.0)

Published 2026-07-03. Last modified 2026-09-15.