Samba from version 4.7.0 has a vulnerability that allows a user in a Samba AD domain to crash the KDC when Samba is built in the non-default MIT Kerberos configuration. With this advisory the Samba Team clarify that the MIT Kerberos build of the Samba AD DC is considered experimental. Therefore the Samba Team will not issue security patches for this configuration. Additionally, Samba 4.7.12, 4.8.7 and 4.9.3 have been issued as security releases to prevent building of the AD DC with MIT Kerberos unless –with-experimental-mit-ad-dc is specified to the configure command.
The product does not properly control the allocation and maintenance of a limited resource.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Samba | Samba | 4.7.0 (including) | 4.7.12 (excluding) |
| Samba | Samba | 4.8.0 (including) | 4.8.7 (excluding) |
| Samba | Samba | 4.9.0 (including) | 4.9.3 (excluding) |
| Samba | Ubuntu | upstream | * |
Mitigation of resource exhaustion attacks requires that the target system either:
The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question.
The second solution is simply difficult to effectively institute – and even when properly done, it does not provide a full solution. It simply makes the attack require more resources on the part of the attacker.