NTP before 4.2.8p9 rate limits responses received from the configured sources when rate limiting for all associations is enabled, which allows remote attackers to cause a denial of service (prevent responses from the sources) by sending responses with a spoofed source address.
The product does not properly control the allocation and maintenance of a limited resource.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Ntp | Ntp | 4.2.6 (including) | 4.2.8 (excluding) |
| Ntp | Ntp | 4.3.0 (including) | 4.3.94 (excluding) |
| Ntp | Ntp | 4.2.5-p203 (including) | 4.2.5-p203 (including) |
| Ntp | Ntp | 4.2.5-p204 (including) | 4.2.5-p204 (including) |
| Ntp | Ntp | 4.2.5-p205 (including) | 4.2.5-p205 (including) |
| Ntp | Ntp | 4.2.5-p206 (including) | 4.2.5-p206 (including) |
| Ntp | Ntp | 4.2.5-p207 (including) | 4.2.5-p207 (including) |
| Ntp | Ntp | 4.2.5-p208 (including) | 4.2.5-p208 (including) |
| Ntp | Ntp | 4.2.5-p209 (including) | 4.2.5-p209 (including) |
| Ntp | Ntp | 4.2.5-p210 (including) | 4.2.5-p210 (including) |
| Ntp | Ntp | 4.2.5-p211 (including) | 4.2.5-p211 (including) |
| Ntp | Ntp | 4.2.5-p212 (including) | 4.2.5-p212 (including) |
| Ntp | Ntp | 4.2.5-p213 (including) | 4.2.5-p213 (including) |
| Ntp | Ntp | 4.2.5-p214 (including) | 4.2.5-p214 (including) |
| Ntp | Ntp | 4.2.5-p215 (including) | 4.2.5-p215 (including) |
| Ntp | Ntp | 4.2.5-p216 (including) | 4.2.5-p216 (including) |
| Ntp | Ntp | 4.2.5-p217 (including) | 4.2.5-p217 (including) |
| Ntp | Ntp | 4.2.5-p218 (including) | 4.2.5-p218 (including) |
| Ntp | Ntp | 4.2.5-p219 (including) | 4.2.5-p219 (including) |
| Ntp | Ntp | 4.2.5-p220 (including) | 4.2.5-p220 (including) |
| Ntp | Ntp | 4.2.5-p221 (including) | 4.2.5-p221 (including) |
| Ntp | Ntp | 4.2.5-p222 (including) | 4.2.5-p222 (including) |
| Ntp | Ntp | 4.2.5-p223 (including) | 4.2.5-p223 (including) |
| Ntp | Ntp | 4.2.5-p224 (including) | 4.2.5-p224 (including) |
| Ntp | Ntp | 4.2.5-p225 (including) | 4.2.5-p225 (including) |
| Ntp | Ntp | 4.2.5-p226 (including) | 4.2.5-p226 (including) |
| Ntp | Ntp | 4.2.5-p227 (including) | 4.2.5-p227 (including) |
| Ntp | Ntp | 4.2.5-p228 (including) | 4.2.5-p228 (including) |
| Ntp | Ntp | 4.2.5-p229 (including) | 4.2.5-p229 (including) |
| Ntp | Ntp | 4.2.5-p230 (including) | 4.2.5-p230 (including) |
| Ntp | Ntp | 4.2.5-p231_rc1 (including) | 4.2.5-p231_rc1 (including) |
| Ntp | Ntp | 4.2.5-p232_rc1 (including) | 4.2.5-p232_rc1 (including) |
| Ntp | Ntp | 4.2.5-p233_rc1 (including) | 4.2.5-p233_rc1 (including) |
| Ntp | Ntp | 4.2.5-p234_rc1 (including) | 4.2.5-p234_rc1 (including) |
| Ntp | Ntp | 4.2.5-p235_rc1 (including) | 4.2.5-p235_rc1 (including) |
| Ntp | Ntp | 4.2.5-p236_rc1 (including) | 4.2.5-p236_rc1 (including) |
| Ntp | Ntp | 4.2.5-p237_rc1 (including) | 4.2.5-p237_rc1 (including) |
| Ntp | Ntp | 4.2.5-p238_rc1 (including) | 4.2.5-p238_rc1 (including) |
| Ntp | Ntp | 4.2.5-p239_rc1 (including) | 4.2.5-p239_rc1 (including) |
| Ntp | Ntp | 4.2.5-p240_rc1 (including) | 4.2.5-p240_rc1 (including) |
| Ntp | Ntp | 4.2.5-p241_rc1 (including) | 4.2.5-p241_rc1 (including) |
| Ntp | Ntp | 4.2.5-p242_rc1 (including) | 4.2.5-p242_rc1 (including) |
| Ntp | Ntp | 4.2.5-p243_rc1 (including) | 4.2.5-p243_rc1 (including) |
| Ntp | Ntp | 4.2.5-p244_rc1 (including) | 4.2.5-p244_rc1 (including) |
| Ntp | Ntp | 4.2.5-p245_rc1 (including) | 4.2.5-p245_rc1 (including) |
| Ntp | Ntp | 4.2.5-p246_rc1 (including) | 4.2.5-p246_rc1 (including) |
| Ntp | Ntp | 4.2.5-p247_rc1 (including) | 4.2.5-p247_rc1 (including) |
| Ntp | Ntp | 4.2.5-p248_rc1 (including) | 4.2.5-p248_rc1 (including) |
| Ntp | Ntp | 4.2.5-p249_rc1 (including) | 4.2.5-p249_rc1 (including) |
| Ntp | Ntp | 4.2.5-p250_rc1 (including) | 4.2.5-p250_rc1 (including) |
| Ntp | Ntp | 4.2.8 (including) | 4.2.8 (including) |
| Ntp | Ntp | 4.2.8-p1 (including) | 4.2.8-p1 (including) |
| Ntp | Ntp | 4.2.8-p1-beta1 (including) | 4.2.8-p1-beta1 (including) |
| Ntp | Ntp | 4.2.8-p1-beta2 (including) | 4.2.8-p1-beta2 (including) |
| Ntp | Ntp | 4.2.8-p1-beta3 (including) | 4.2.8-p1-beta3 (including) |
| Ntp | Ntp | 4.2.8-p1-beta4 (including) | 4.2.8-p1-beta4 (including) |
| Ntp | Ntp | 4.2.8-p1-beta5 (including) | 4.2.8-p1-beta5 (including) |
| Ntp | Ntp | 4.2.8-p1-rc1 (including) | 4.2.8-p1-rc1 (including) |
| Ntp | Ntp | 4.2.8-p1-rc2 (including) | 4.2.8-p1-rc2 (including) |
| Ntp | Ntp | 4.2.8-p2 (including) | 4.2.8-p2 (including) |
| Ntp | Ntp | 4.2.8-p2-rc1 (including) | 4.2.8-p2-rc1 (including) |
| Ntp | Ntp | 4.2.8-p2-rc2 (including) | 4.2.8-p2-rc2 (including) |
| Ntp | Ntp | 4.2.8-p2-rc3 (including) | 4.2.8-p2-rc3 (including) |
| Ntp | Ntp | 4.2.8-p3 (including) | 4.2.8-p3 (including) |
| Ntp | Ntp | 4.2.8-p3-rc1 (including) | 4.2.8-p3-rc1 (including) |
| Ntp | Ntp | 4.2.8-p3-rc2 (including) | 4.2.8-p3-rc2 (including) |
| Ntp | Ntp | 4.2.8-p3-rc3 (including) | 4.2.8-p3-rc3 (including) |
| Ntp | Ntp | 4.2.8-p4 (including) | 4.2.8-p4 (including) |
| Ntp | Ntp | 4.2.8-p5 (including) | 4.2.8-p5 (including) |
| Ntp | Ntp | 4.2.8-p6 (including) | 4.2.8-p6 (including) |
| Ntp | Ntp | 4.2.8-p7 (including) | 4.2.8-p7 (including) |
| Ntp | Ntp | 4.2.8-p8 (including) | 4.2.8-p8 (including) |
| Red Hat Enterprise Linux 6 | RedHat | ntp-0:4.2.6p5-10.el6_8.2 | * |
| Red Hat Enterprise Linux 7 | RedHat | ntp-0:4.2.6p5-25.el7_3.1 | * |
| Ntp | Ubuntu | esm-infra-legacy/trusty | * |
| Ntp | Ubuntu | esm-infra/xenial | * |
| Ntp | Ubuntu | precise | * |
| Ntp | Ubuntu | trusty | * |
| Ntp | Ubuntu | trusty/esm | * |
| Ntp | Ubuntu | upstream | * |
| Ntp | Ubuntu | vivid/stable-phone-overlay | * |
| Ntp | Ubuntu | xenial | * |
| Ntp | Ubuntu | yakkety | * |
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.