CVE-2018-16840: Canonical Ubuntu Linux

Critical severity, CVSS 9.8. EPSS: 3.4% chance of exploitation in the next 30 days.

A heap use-after-free flaw was found in curl versions from 7.59.0 through 7.61.1 in the code related to closing an easy handle. When closing and cleaning up an 'easy' handle in the `Curl_close()` function, the library code first frees a struct (without nulling the pointer) and might then subsequently erroneously write to a struct field within that already freed struct.

Affected products

• Canonical Ubuntu Linux: version 14.04 only; version 16.04 only; version 18.04 only; version 18.10 only
• Haxx Curl: from 7.59.0, before 7.62.0 (fixed in 7.62.0)

Published 2018-10-31. Last modified 2026-06-17.