CVE-2026-9079: Haxx Curl

Critical severity, CVSS 9.8. EPSS: 0.6% chance of exploitation in the next 30 days.

libcurl had a flaw that when instructed to clear proxy authentication credentials which made it not do so, leaving the old credentials around to get used for subsequent transfers that should not know nor use them.

Affected products

• Haxx Curl: from 8.8.0, before 8.21.0 (fixed in 8.21.0)

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