CVE-2021-0289

Junos OS: User-defined ARP Policer isn't applied on Aggregated Ethernet (AE) interface until firewall process is restarted

MEDIUM

5.3

CVSS Score

Published: July 15, 2021 at 08:01 PM UTC

Updated: June 17, 2026 at 03:29 AM UTC

228 products affected across 2 vendorsJunosSRX5600SRX5800

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Severity

MEDIUM5.3

Exploit prediction

EPSS 0.3%

Description

When user-defined ARP Policer is configured and applied on one or more Aggregated Ethernet (AE) interface units, a Time-of-check Time-of-use (TOCTOU) Race Condition vulnerability between the Device Control Daemon (DCD) and firewall process (dfwd) daemons of Juniper Networks Junos OS allows an attacker to bypass the user-defined ARP Policer. In this particular case the User ARP policer is replaced with default ARP policer. To review the desired ARP Policers and actual state one can run the command "show interfaces <> extensive" and review the output. See further details below. An example output is: show interfaces extensive | match policer Policer: Input: __default_arp_policer__ <<< incorrect if user ARP Policer was applied on an AE interface and the default ARP Policer is displayed Policer: Input: jtac-arp-ae5.317-inet-arp <<< correct if user ARP Policer was applied on an AE interface For all platforms, except SRX Series: This issue affects Juniper Networks Junos OS: All versions 5.6R1 and all later versions prior to 18.4 versions prior to 18.4R2-S9, 18.4R3-S9 with the exception of 15.1 versions 15.1R7-S10 and later versions; 19.4 versions prior to 19.4R3-S3; 20.1 versions prior to 20.1R3; 20.2 versions prior to 20.2R3-S2; 20.3 version 20.3R1 and later versions; 20.4 versions prior to 20.4R3; 21.1 versions prior to 21.1R2; This issue does not affect Juniper Networks Junos OS versions prior to 5.6R1. On SRX Series this issue affects Juniper Networks Junos OS: 18.4 versions prior to 18.4R2-S9, 18.4R3-S9; 19.4 versions prior to 19.4R3-S4; 20.1 versions prior to 20.1R3; 20.2 versions prior to 20.2R3-S2; 20.3 version 20.3R1 and later versions; 20.4 versions prior to 20.4R3; 21.1 versions prior to 21.1R2. This issue does not affect 18.4 versions prior to 18.4R1 on SRX Series. This issue does not affect Junos OS Evolved.

Affected

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

Junos · Juniper Networks

95%

15.1 ≤ v < 15.1R7-S1015.2 ≤ v < 18.416.1R1 ≤ v < 16.1*16.2R1 ≤ v < 16.2*17.1R1 ≤ v < 17.1*17.2R1 ≤ v < 17.2*17.3R1 ≤ v < 17.3*17.4R1 ≤ v < 17.4*18.1R1 ≤ v < 18.1*18.2R1 ≤ v < 18.2*18.3R1 ≤ v < 18.3*18.4 ≤ v < 18.4R2-S9, 18.4R3-S919.4 ≤ v < 19.4R3-S320.1 ≤ v < 20.1R320.2 ≤ v < 20.2R3-S220.3R1 ≤ v < 20.3*20.4 ≤ v < 20.4R321.1 ≤ v < 21.1R25.7 ≤ v < 15.115.1 16.1R1 16.2R1 17.1R1 17.2R1 17.3R1 17.4R1 18.1R1 18.2R1 18.3R1 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 r1-s7 18.4 r2 18.4 r2-s1 18.4 r2-s2 18.4 r2-s3 18.4 r2-s4 18.4 r2-s5 18.4 r2-s6 18.4 r2-s7 18.4 r2-s8 18.4 r3 18.4 r3-s1 18.4 r3-s2 18.4 r3-s3 18.4 r3-s4 18.4 r3-s5 18.4 r3-s6 18.4 r3-s7 18.4 r3-s8 19.4 19.4 r1 19.4 r1-s1 19.4 r1-s2 19.4 r1-s3 19.4 r2 19.4 r2-s1 19.4 r2-s2 19.4 r2-s3 19.4 r3 19.4 r3-s1 19.4 r3-s2 19.4 r3-s3 20.1 20.1 r1 20.1 r1-s1 20.1 r1-s2 20.1 r1-s3 20.1 r1-s4 20.1 r2 20.1 r2-s1 20.2 20.2 r1 20.2 r1-s1 20.2 r1-s2 20.2 r1-s3 20.2 r2 20.2 r2-s1 20.2 r2-s2 20.2 r2-s3 20.2 r3 20.2 r3-s1 20.3 r1 20.3 r1-s1 20.3 r2 20.3R1 20.4 20.4 r1 20.4 r1-s1 20.4 r2 20.4 r2-s1 21.1 21.1 r1 21.1 r1-s1 5.6 r1

Affected range stops below 15.1, so it looks safe — our inference, not a vendor statement

Affected range stops below 15.1R7-S10, so it looks safe — our inference, not a vendor statement

Affected range stops below 16.1*, so it looks safe — our inference, not a vendor statement

Affected range stops below 16.2*, so it looks safe — our inference, not a vendor statement

Affected range stops below 17.1*, so it looks safe — our inference, not a vendor statement

Affected range stops below 17.2*, so it looks safe — our inference, not a vendor statement

Affected range stops below 17.3*, so it looks safe — our inference, not a vendor statement

Affected range stops below 17.4*, so it looks safe — our inference, not a vendor statement

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

Affected range stops below 18.2*, so it looks safe — our inference, not a vendor statement

Affected range stops below 18.3*, so it looks safe — our inference, not a vendor statement

Affected range stops below 18.4, so it looks safe — our inference, not a vendor statement

Affected range stops below 18.4R2-S9, 18.4R3-S9, so it looks safe — our inference, not a vendor statement

Affected range stops below 19.4R3-S3, so it looks safe — our inference, not a vendor statement

Affected range stops below 20.1R3, so it looks safe — our inference, not a vendor statement

Vendor states this is fixed in 20.2 (unaffected)

Affected range stops below 20.2R3-S2, so it looks safe — our inference, not a vendor statement

Affected range stops below 20.3*, so it looks safe — our inference, not a vendor statement

Affected range stops below 20.4R3, so it looks safe — our inference, not a vendor statement

Affected range stops below 21.1R2, so it looks safe — our inference, not a vendor statement

Vendor states this is fixed in 5.6R1 (unaffected)

juniper-acx1000 (environment) · juniper-acx1100 (environment) · juniper-acx2000 (environment) · juniper-acx2100 (environment) · juniper-acx2200 (environment) · juniper-acx4000 (environment) · juniper-acx500 (environment) · juniper-acx5000 (environment) · juniper-acx5048 (environment) · juniper-acx5096 (environment) · juniper-acx5400 (environment) · juniper-acx5448 (environment) · juniper-acx5800 (environment) · juniper-acx6300 (environment) · juniper-acx6360 (environment) · juniper-acx710 (environment) · juniper-atp400 (environment) · juniper-atp700 (environment) · juniper-csrx (environment) · juniper-ctp150 (environment) · juniper-ctp2008 (environment) · juniper-ctp2024 (environment) · juniper-ctp2056 (environment) · juniper-dx (environment) · juniper-ex-rps (environment) · juniper-ex2200 (environment) · juniper-ex2200-c (environment) · juniper-ex2200-vc (environment) · juniper-ex2300 (environment) · juniper-ex2300-c (environment) · juniper-ex2300m (environment) · juniper-ex3200 (environment) · juniper-ex3300 (environment) · juniper-ex3300-vc (environment) · juniper-ex3400 (environment) · juniper-ex4200 (environment) · juniper-ex4200-vc (environment) · juniper-ex4300 (environment) · juniper-ex4300-24p (environment) · juniper-ex4300-24p-s (environment) · juniper-ex4300-24t (environment) · juniper-ex4300-24t-s (environment) · juniper-ex4300-32f (environment) · juniper-ex4300-32f-dc (environment) · juniper-ex4300-32f-s (environment) · juniper-ex4300-48mp (environment) · juniper-ex4300-48mp-s (environment) · juniper-ex4300-48p (environment) · juniper-ex4300-48p-s (environment) · juniper-ex4300-48t (environment) · juniper-ex4300-48t-afi (environment) · juniper-ex4300-48t-dc (environment) · juniper-ex4300-48t-dc-afi (environment) · juniper-ex4300-48t-s (environment) · juniper-ex4300-48tafi (environment) · juniper-ex4300-48tdc (environment) · juniper-ex4300-48tdc-afi (environment) · juniper-ex4300-mp (environment) · juniper-ex4300-vc (environment) · juniper-ex4300m 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juniper-idp75 (environment) · juniper-idp800 (environment) · juniper-idp8200 (environment) · juniper-infranet-controller-4000 (environment) · juniper-infranet-controller-4500 (environment) · juniper-infranet-controller-6000 (environment) · juniper-infranet-controller-6500 (environment) · juniper-jatp (environment) · juniper-junos-space-ja1500-appliance (environment) · juniper-junos-space-ja2500-appliance (environment) · juniper-ln1000 (environment) · juniper-ln2600 (environment) · juniper-m10i (environment) · juniper-m120 (environment) · juniper-m320 (environment) · juniper-m7i (environment) · juniper-mag2600-gateway (environment) · juniper-mag4610-gateway (environment) · juniper-mag6610-gateway (environment) · juniper-mag6611-gateway (environment) · juniper-mx (environment) · juniper-mx10 (environment) · juniper-mx10000 (environment) · juniper-mx10003 (environment) · juniper-mx10008 (environment) · juniper-mx10016 (environment) · juniper-mx104 (environment) · juniper-mx150 (environment) · juniper-mx2008 (environment) · juniper-mx2010 (environment) · juniper-mx2020 (environment) · juniper-mx204 (environment) · juniper-mx240 (environment) · juniper-mx40 (environment) · juniper-mx480 (environment) · juniper-mx5 (environment) · juniper-mx80 (environment) · juniper-mx960 (environment) · juniper-netscreen-5200 (environment) · juniper-netscreen-5400 (environment) · juniper-netscreen-5gt (environment) · juniper-netscreen-idp (environment) · juniper-netscreen-idp-10 (environment) · juniper-netscreen-idp-100 (environment) · juniper-netscreen-idp-1000 (environment) · juniper-netscreen-idp-500 (environment) · juniper-nfx (environment) · juniper-nfx150 (environment) · juniper-nfx250 (environment) · juniper-nfx350 (environment) · juniper-nsm3000 (environment) · juniper-nsmexpress (environment) · juniper-ocx1100 (environment) · juniper-ptx1000 (environment) · juniper-ptx1000-72q (environment) · juniper-ptx10000 (environment) · juniper-ptx10001 (environment) · juniper-ptx10001-36mr (environment) · juniper-ptx100016 (environment) · juniper-ptx10002 (environment) · juniper-ptx10002-60c (environment) · juniper-ptx10003 (environment) · juniper-ptx10003-160c (environment) · juniper-ptx10003-80c (environment) · juniper-ptx10003-81cd (environment) · juniper-ptx10004 (environment) · juniper-ptx10008 (environment) · juniper-ptx10016 (environment) · juniper-ptx3000 (environment) · juniper-ptx5000 (environment) · juniper-qfx10000 (environment) · juniper-qfx10002 (environment) · juniper-qfx10002-32q (environment) · juniper-qfx10002-60c (environment) · juniper-qfx10002-72q (environment) · juniper-qfx10008 (environment) · juniper-qfx10016 (environment) · juniper-qfx3000-g (environment) · juniper-qfx3000-m (environment) · juniper-qfx3008-i (environment) · juniper-qfx3100 (environment) · juniper-qfx3500 (environment) · juniper-qfx3600 (environment) · juniper-qfx3600-i (environment) · juniper-qfx5100 (environment) · juniper-qfx5100-96s (environment) · juniper-qfx5110 (environment) · juniper-qfx5120 (environment) · juniper-qfx5130 (environment) · juniper-qfx5200 (environment) · juniper-qfx5200-32c (environment) · juniper-qfx5200-48y (environment) · juniper-qfx5210 (environment) · juniper-qfx5210-64c (environment) · juniper-qfx5220 (environment) · juniper-router-m10 (environment) · juniper-router-m16 (environment) · juniper-router-m20 (environment) · juniper-router-m40 (environment) · juniper-router-m5 (environment) · juniper-secure-access-2000 (environment) · juniper-secure-access-2500 (environment) · juniper-secure-access-4000 (environment) · juniper-secure-access-4500 (environment) · juniper-secure-access-6000 (environment) · juniper-secure-access-6500 (environment) · juniper-secure-access-700 (environment) · juniper-srx100 (environment) · juniper-srx110 (environment) · juniper-srx1400 (environment) · juniper-srx1500 (environment) · juniper-srx210 (environment) · juniper-srx220 (environment) · juniper-srx240 (environment) · juniper-srx240h2 (environment) · juniper-srx300 (environment) · juniper-srx320 (environment) · juniper-srx340 (environment) · juniper-srx3400 (environment) · juniper-srx345 (environment) · juniper-srx3600 (environment) · juniper-srx380 (environment) · juniper-srx4000 (environment) · juniper-srx4100 (environment) · juniper-srx4200 (environment) · juniper-srx4600 (environment) · juniper-srx5000 (environment) · juniper-srx5400 (environment) · juniper-srx550 (environment) · juniper-srx550-hm (environment) · juniper-srx550m (environment) · juniper-srx5600 (environment) · juniper-srx5800 (environment) · juniper-srx650 (environment) · juniper-t1600 (environment) · juniper-t320 (environment) · juniper-t4000 (environment) · juniper-t640 (environment) · juniper-xre200 (environment)

Acx1000 · Juniperdevice

80%

All versions

Acx1100 · Juniperdevice

80%

All versions

Acx2000 · Juniperdevice

80%

All versions

Acx2100 · Juniperdevice

80%

All versions