CVE-2020-1685

Junos OS: EX4600, QFX5K Series: Stateless firewall filter matching 'user-vlan-id' will cause incomplete discard action

MEDIUM

5.8

CVSS Score

Published: October 16, 2020 at 08:31 PM UTC

Updated: June 17, 2026 at 03:02 AM UTC

8 products affected across 2 vendorsJunosQfx5200Qfx5110

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Severity

MEDIUM5.8

Exploit prediction

EPSS 0.8%

Description

When configuring stateless firewall filters in Juniper Networks EX4600 and QFX 5000 Series devices using Virtual Extensible LAN protocol (VXLAN), the discard action will fail to discard traffic under certain conditions. Given a firewall filter configuration similar to: family ethernet-switching { filter L2-VLAN { term ALLOW { from { user-vlan-id 100; } then { accept; } } term NON-MATCH { then { discard; } } when there is only one term containing a 'user-vlan-id' match condition, and no other terms in the firewall filter except discard, the discard action for non-matching traffic will only discard traffic with the same VLAN ID specified under 'user-vlan-id'. Other traffic (e.g. VLAN ID 200) will not be discarded. This unexpected behavior can lead to unintended traffic passing through the interface where the firewall filter is applied. This issue only affects systems using VXLANs. This issue affects Juniper Networks Junos OS on QFX5K Series: 18.1 versions prior to 18.1R3-S7, except 18.1R3; 18.2 versions prior to 18.2R2-S7, 18.2R3-S1; 18.3 versions prior to 18.3R1-S5, 18.3R2-S4, 18.3R3; 18.4 versions prior to 18.4R1-S7, 18.4R2-S1, 18.4R3; 19.1 versions prior to 19.1R1-S5, 19.1R2; 19.2 versions prior to 19.2R1-S5, 19.2R2.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Junos · Juniper Networks

95%

18.1 ≤ v < 18.1R3-S718.2 ≤ v < 18.2R2-S7, 18.2R3-S118.3 ≤ v < 18.3R1-S5, 18.3R2-S4, 18.3R318.4 ≤ v < 18.4R1-S7, 18.4R2-S1, 18.4R319.1 ≤ v < 19.1R1-S5, 19.1R219.2 ≤ v < 19.2R1-S5, 19.2R218.1 18.1 r1 18.1 r2 18.1 r2-s1 18.1 r2-s2 18.1 r2-s4 18.1 r3 18.1 r3-s1 18.1 r3-s2 18.1 r3-s3 18.1 r3-s4 18.1 r3-s6 18.2 18.2 r1 18.2 r1-s3 18.2 r1-s4 18.2 r1-s5 18.2 r2 18.2 r2-s1 18.2 r2-s2 18.2 r2-s3 18.2 r2-s4 18.2 r2-s5 18.2 r2-s6 18.2 r3 18.3 18.3 r1 18.3 r1-s1 18.3 r1-s2 18.3 r1-s3 18.3 r1-s4 18.3 r2 18.3 r2-s1 18.3 r2-s2 18.3 r2-s3 18.4 18.4 r1 18.4 r1-s1 18.4 r1-s2 18.4 r1-s3 18.4 r1-s4 18.4 r1-s5 18.4 r1-s6 18.4 r2 19.1 19.1 r1 19.1 r1-s1 19.1 r1-s2 19.1 r1-s3 19.1 r1-s4 19.2 19.2 r1 19.2 r1-s1 19.2 r1-s2 19.2 r1-s3 19.2 r1-s4

Vendor states this is fixed in 18.1R3 (unaffected)

Affected range stops below 18.1R3-S7, so it looks safe — our inference, not a vendor statement

Affected range stops below 18.2R2-S7, 18.2R3-S1, so it looks safe — our inference, not a vendor statement

Affected range stops below 18.3R1-S5, 18.3R2-S4, 18.3R3, so it looks safe — our inference, not a vendor statement

Affected range stops below 18.4R1-S7, 18.4R2-S1, 18.4R3, so it looks safe — our inference, not a vendor statement

Affected range stops below 19.1R1-S5, 19.1R2, so it looks safe — our inference, not a vendor statement

Affected range stops below 19.2R1-S5, 19.2R2, so it looks safe — our inference, not a vendor statement

juniper-qfx5100 (environment) · juniper-qfx5110 (environment) · juniper-qfx5120 (environment) · juniper-qfx5130 (environment) · juniper-qfx5200 (environment) · juniper-qfx5210 (environment) · juniper-qfx5220 (environment)

Qfx5100 · Juniperdevice

80%

All versions

Qfx5110 · Juniperdevice

80%

All versions

Qfx5120 · Juniperdevice

80%

All versions

Qfx5130 · Juniperdevice

80%

All versions