CVE-2018-16841: Canonical Ubuntu Linux

Medium severity, CVSS 6.5. EPSS: 4.6% chance of exploitation in the next 30 days.

Samba from version 4.3.0 and before versions 4.7.12, 4.8.7 and 4.9.3 are vulnerable to a denial of service. When configured to accept smart-card authentication, Samba's KDC will call talloc_free() twice on the same memory if the principal in a validly signed certificate does not match the principal in the AS-REQ. This is only possible after authentication with a trusted certificate. talloc is robust against further corruption from a double-free with talloc_free() and directly calls abort(), terminating the KDC process.

Affected products

• Canonical Ubuntu Linux: version 12.04 only; version 14.04 only; version 16.04 only; version 18.04 only; version 18.10 only
• Debian Debian Linux: version 9.0 only
• Samba Samba: from 4.3.0, before 4.7.12 (fixed in 4.7.12); from 4.8.0, before 4.8.7 (fixed in 4.8.7); from 4.9.0, before 4.9.3 (fixed in 4.9.3)

Published 2018-11-28. Last modified 2026-06-17.