CVE-2018-16851: Canonical Ubuntu Linux

Medium severity, CVSS 6.5. EPSS: 3.3% chance of exploitation in the next 30 days.

Samba from version 4.0.0 and before versions 4.7.12, 4.8.7, 4.9.3 is vulnerable to a denial of service. During the processing of an LDAP search before Samba's AD DC returns the LDAP entries to the client, the entries are cached in a single memory object with a maximum size of 256MB. When this size is reached, the Samba process providing the LDAP service will follow the NULL pointer, terminating the process. There is no further vulnerability associated with this issue, merely a denial of service.

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 8.0 only; version 9.0 only
• Samba Samba: from 4.0.0, 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.