CVE-2026-5773: Haxx Curl

High severity, CVSS 7.5. EPSS: 0.7% chance of exploitation in the next 30 days.

libcurl might in some circumstances reuse the wrong connection for SMB(S) transfers. 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 network transfer operation that was requested by an application could wrongfully reuse an existing SMB connection to the same server that was using a different "share" than the new subsequent transfer should. This could in unlucky situations lead to the download of the wrong file or the upload of a file to the wrong place. When this happens, the same credentials are used and the server name is the same.

Affected products

• Haxx Curl: from 7.40.0, before 8.20.0 (fixed in 8.20.0)

Published 2026-05-13. Last modified 2026-09-15.