Improper Handling of Unexpected Data in the firewall policer of Juniper Networks Junos OS on EX4300 switches allows matching traffic to exceed set policer limits, possibly leading to a limited Denial of Service (DoS) condition. When the firewall policer discard action fails on a Layer 2 port, it will allow traffic to pass even though it exceeds set policer limits. Traffic will not get discarded, and will be forwarded even though a policer discard action is configured. When the issue occurs, traffic is not discarded as desired, which can be observed by comparing the Input bytes with the Output bytes using the following command: user@junos> monitor interface traffic Interface Link Input bytes (bps) Output bytes (bps) ge-0/0/0 Up 37425422 (82616) 37425354 (82616) <<<< egress ge-0/0/1 Up 37425
The following software releases have been updated to resolve this specific issue: Junos OS 17.3R3-S10, 17.4R3-S3, 18.1R3-S11, 18.2R3-S6, 18.3R3-S4, 18.4R3-S6, 19.1R3-S3, 19.2R3-S1, 19.3R3-S1, 19.4R3, 20.1R2, 20.2R2, 20.3R1, and all subsequent releases.
There are no viable workarounds for this issue.
| Product | Vulnerable range | Fixed version | Advisory |
|---|---|---|---|
| Juniper Networks Junos OS | >=unspecified<17.3R3-S10 | 17.3R3-S10 | advisory ↗ |
| Juniper Networks Junos OS | >=17.4<17.4R3-S3 | 17.4R3-S3 | advisory ↗ |
| Juniper Networks Junos OS | >=18.1<18.1R3-S11 | 18.1R3-S11 | advisory ↗ |
| Juniper Networks Junos OS | >=18.2<18.2R3-S6 | 18.2R3-S6 | advisory ↗ |
| Juniper Networks Junos OS | >=18.3<18.3R3-S4 | 18.3R3-S4 | advisory ↗ |
| Juniper Networks Junos OS | >=18.4<18.4R3-S6 | 18.4R3-S6 | advisory ↗ |
| Juniper Networks Junos OS | >=19.1<19.1R3-S3 | 19.1R3-S3 | advisory ↗ |
| Juniper Networks Junos OS | >=19.2<19.2R3-S1 | 19.2R3-S1 | advisory ↗ |
| Juniper Networks Junos OS | >=19.3<19.3R3-S1 | 19.3R3-S1 | advisory ↗ |
| Juniper Networks Junos OS | >=19.4<19.4R3 | 19.4R3 | advisory ↗ |
| Juniper Networks Junos OS | >=20.1<20.1R2 | 20.1R2 | advisory ↗ |
| Juniper Networks Junos OS | >=20.2<20.2R2 | 20.2R2 | advisory ↗ |