CVE-2021-0247

Junos OS: PTX Series, QFX Series: Due to a race condition input loopback firewall filters applied to interfaces may not operate even when listed in the running configuration.

MEDIUM

5.5

CVSS Score

Published: April 22, 2021 at 07:37 PM UTC

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

20 products affected across 2 vendorsJunosQfx5200Qfx5110

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Severity

MEDIUM5.5

Exploit prediction

EPSS 0.6%

Description

A Race Condition (Concurrent Execution using Shared Resource with Improper Synchronization) vulnerability in the firewall process (dfwd) of Juniper Networks Junos OS allows an attacker to bypass the firewall rule sets applied to the input loopback filter on any interfaces of a device. This issue is detectable by reviewing the PFE firewall rules, as well as the firewall counters and seeing if they are incrementing or not. For example: show firewall Filter: __default_bpdu_filter__ Filter: FILTER-INET-01 Counters: Name Bytes Packets output-match-inet 0 0 <<<<<< missing firewall packet count This issue affects: Juniper Networks Junos OS 14.1X53 versions prior to 14.1X53-D53 on QFX Series; 14.1 versions 14.1R1 and later versions prior to 15.1 versions prior to 15.1R7-S6 on QFX Series, PTX Series; 15.1X53 versions prior to 15.1X53-D593 on QFX Series; 16.1 versions prior to 16.1R7-S7 on QFX Series, PTX Series; 16.2 versions prior to 16.2R2-S11, 16.2R3 on QFX Series, PTX Series; 17.1 versions prior to 17.1R2-S11, 17.1R3-S2 on QFX Series, PTX Series; 17.2 versions prior to 17.2R1-S9, 17.2R3-S3 on QFX Series, PTX Series; 17.3 versions prior to 17.3R2-S5, 17.3R3-S7 on QFX Series, PTX Series; 17.4 versions prior to 17.4R2-S9, 17.4R3 on QFX Series, PTX Series; 18.1 versions prior to 18.1R3-S9 on QFX Series, PTX Series; 18.2 versions prior to 18.2R2-S6, 18.2R3-S3 on QFX Series, PTX Series; 18.3 versions prior to 18.3R1-S7, 18.3R2-S3, 18.3R3-S1 on QFX Series, PTX Series; 18.4 versions prior to 18.4R1-S5, 18.4R2-S3, 18.4R2-S7, 18.4R3 on QFX Series, PTX Series; 19.1 versions prior to 19.1R1-S4, 19.1R2-S1, 19.1R3 on QFX Series, PTX Series; 19.2 versions prior to 19.2R1-S3, 19.2R2 on QFX Series, PTX Series.

Affected

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

Junos · Juniper Networks

95%

14.1R1 ≤ v < 14.1*14.1X53 ≤ v < 14.1X53-D5315.1 ≤ v < 15.1R7-S615.1X53 ≤ v < 15.1X53-D59316.1 ≤ v < 16.1R7-S716.2 ≤ v < 16.2R2-S11, 16.2R317.1 ≤ v < 17.1R2-S11, 17.1R3-S217.2 ≤ v < 17.2R1-S9, 17.2R3-S317.3 ≤ v < 17.3R2-S5, 17.3R3-S717.4 ≤ v < 17.4R2-S9, 17.4R318.1 ≤ v < 18.1R3-S918.2 ≤ v < 18.2R2-S6, 18.2R3-S318.3 ≤ v < 18.3R1-S7, 18.3R2-S3, 18.3R3-S118.4 ≤ v < 18.4R1-S5, 18.4R2-S3, 18.4R319.1 ≤ v < 19.1R1-S4, 19.1R2-S1, 19.1R319.2 ≤ v < 19.2R1-S3, 19.2R214.1 14.1 r1 14.1 r2 14.1 r3 14.1 r4 14.1 r5 14.1 r6 14.1 r7 14.1 r8 14.1 r8-s3 14.1 r9 14.1R1 14.1X5314.1x5314.1x53 d10 14.1x53 d15 14.1x53 d16 14.1x53 d20 14.1x53 d25 14.1x53 d26 14.1x53 d27 14.1x53 d30 14.1x53 d34 14.1x53 d35 14.1x53 d38 14.1x53 d40 14.1x53 d42 14.1x53 d43 14.1x53 d44 14.1x53 d45 14.1x53 d4614.1x53 d4714.1x53 d48 14.1x53 d49 14.1x53 d50 14.1x53 d51 14.1x53 d52 14.2 14.2 r 14.2 r1 14.2 r2 14.2 r3 14.2 r4 14.2 r5 14.2 r6 14.2 r7 14.2 r7-s6 14.2 r7-s7 14.2 r7-s8 14.2 r8 15.1 15.1 a1 15.1 f 15.1 f1 15.1 f2 15.1 f2-s1 15.1 f2-s2 15.1 f2-s3 15.1 f2-s4 15.1 f3 15.1 f4 15.1 f5 15.1 f5-s7 15.1 f6 15.1 f6-s1 15.1 f6-s10 15.1 f6-s12 15.1 f6-s2 15.1 f6-s3 15.1 f6-s4 15.1 f6-s5 15.1 f6-s6 15.1 f6-s7 15.1 f6-s8 15.1 f6-s9 15.1 f7 15.1 r 15.1 r1 15.1 r2 15.1 r3 15.1 r4 15.1 r4-s7 15.1 r4-s8 15.1 r4-s9 15.1 r5 15.1 r5-s1 15.1 r5-s3 15.1 r5-s5 15.1 r5-s6 15.1 r6 15.1 r6-s1 15.1 r6-s2 15.1 r6-s3 15.1 r6-s4 15.1 r6-s6 15.1 r7 15.1 r7-s1 15.1 r7-s2 15.1 r7-s3 15.1 r7-s4 15.1 r7-s5 15.1X5315.1x5315.1x53 d10 15.1x53 d20 15.1x53 d21 15.1x53 d210 15.1x53 d230 15.1x53 d231 15.1x53 d23215.1x53 d23315.1x53 d234 15.1x53 d235 15.1x53 d236 15.1x53 d237 15.1x53 d25 15.1x53 d30 15.1x53 d31 15.1x53 d32 15.1x53 d33 15.1x53 d34 15.1x53 d40 15.1x53 d45 15.1x53 d47 15.1x53 d470 15.1x53 d471 15.1x53 d48 15.1x53 d490 15.1x53 d495 15.1x53 d50 15.1x53 d51 15.1x53 d52 15.1x53 d55 15.1x53 d56 15.1x53 d57 15.1x53 d5815.1x53 d5915.1x53 d590 15.1x53 d591 15.1x53 d592 15.1x53 d60 15.1x53 d61 15.1x53 d62 15.1x53 d63 15.1x53 d64 15.1x53 d65 15.1x53 d6615.1x53 d6715.1x53 d68 15.1x53 d69 15.1x53 d70 16.1 16.1 r 16.1 r1 16.1 r2 16.1 r3 16.1 r3-s10 16.1 r3-s11 16.1 r3-s8 16.1 r4 16.1 r4-s12 16.1 r4-s2 16.1 r4-s3 16.1 r4-s4 16.1 r4-s6 16.1 r4-s8 16.1 r4-s9 16.1 r5 16.1 r5-s4 16.1 r6 16.1 r6-s1 16.1 r6-s3 16.1 r6-s4 16.1 r6-s6 16.1 r7 16.1 r7-s2 16.1 r7-s3 16.1 r7-s4 16.1 r7-s5 16.1 r7-s6 16.2 16.2 r1 16.2 r1-s6 16.2 r2 16.2 r2-s1 16.2 r2-s10 16.2 r2-s2 16.2 r2-s5 16.2 r2-s6 16.2 r2-s7 16.2 r2-s8 16.2 r2-s9 17.1 17.1 r1 17.1 r1-s7 17.1 r2 17.1 r2-s1 17.1 r2-s10 17.1 r2-s2 17.1 r2-s3 17.1 r2-s4 17.1 r2-s5 17.1 r2-s6 17.1 r2-s7 17.1 r2-s8 17.1 r2-s9 17.1 r3 17.1 r3-s1 17.2 17.2 r1 17.2 r1-s1 17.2 r1-s2 17.2 r1-s3 17.2 r1-s4 17.2 r1-s5 17.2 r1-s6 17.2 r1-s7 17.2 r1-s8 17.2 r2 17.2 r2-s11 17.2 r2-s4 17.2 r2-s6 17.2 r2-s7 17.2 r3 17.2 r3-s1 17.2 r3-s2 17.3 17.3 r1 17.3 r1-s1 17.3 r1-s4 17.3 r2 17.3 r2-s1 17.3 r2-s2 17.3 r2-s3 17.3 r2-s4 17.3 r3 17.3 r3-s1 17.3 r3-s10 17.3 r3-s2 17.3 r3-s3 17.3 r3-s4 17.3 r3-s5 17.3 r3-s6 17.4 17.4 r1 17.4 r1-s1 17.4 r1-s2 17.4 r1-s3 17.4 r1-s4 17.4 r1-s5 17.4 r1-s6 17.4 r1-s7 17.4 r2 17.4 r2-s1 17.4 r2-s10 17.4 r2-s11 17.4 r2-s2 17.4 r2-s3 17.4 r2-s4 17.4 r2-s5 17.4 r2-s6 17.4 r2-s7 17.4 r2-s8 18.1 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-s10 18.1 r3-s11 18.1 r3-s2 18.1 r3-s3 18.1 r3-s4 18.1 r3-s5 18.1 r3-s6 18.1 r3-s7 18.1 r3-s8 18.2 18.2 r1 18.2 r1-s2 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 r3 18.2 r3-s1 18.2 r3-s2 18.3 18.3 r1 18.3 r1-s1 18.3 r1-s2 18.3 r1-s3 18.3 r1-s4 18.3 r1-s5 18.3 r1-s6 18.3 r3 18.4 18.4 r2 18.4 r2-s1 18.4 r2-s2 19.1 19.1 r1 19.1 r1-s1 19.1 r1-s2 19.1 r1-s3 19.1 r2 19.2 19.2 r1 19.2 r1-s1 19.2 r1-s2

Affected range stops below 14.1*, so it looks safe — our inference, not a vendor statement

Affected range stops below 14.1X53-D53, so it looks safe — our inference, not a vendor statement

Affected range stops below 15.1R7-S6, so it looks safe — our inference, not a vendor statement

Affected range stops below 15.1X53-D593, so it looks safe — our inference, not a vendor statement

Affected range stops below 16.1R7-S7, so it looks safe — our inference, not a vendor statement

Affected range stops below 16.2R2-S11, 16.2R3, so it looks safe — our inference, not a vendor statement

Affected range stops below 17.1R2-S11, 17.1R3-S2, so it looks safe — our inference, not a vendor statement

Affected range stops below 17.2R1-S9, 17.2R3-S3, so it looks safe — our inference, not a vendor statement

Affected range stops below 17.3R2-S5, 17.3R3-S7, so it looks safe — our inference, not a vendor statement

Affected range stops below 17.4R2-S9, 17.4R3, so it looks safe — our inference, not a vendor statement

Affected range stops below 18.1R3-S9, so it looks safe — our inference, not a vendor statement

Affected range stops below 18.2R2-S6, 18.2R3-S3, so it looks safe — our inference, not a vendor statement

Affected range stops below 18.3R1-S7, 18.3R2-S3, 18.3R3-S1, so it looks safe — our inference, not a vendor statement

Affected range stops below 18.4R1-S5, 18.4R2-S3, 18.4R3, so it looks safe — our inference, not a vendor statement

Affected range stops below 19.1R1-S4, 19.1R2-S1, 19.1R3, so it looks safe — our inference, not a vendor statement

Affected range stops below 19.2R1-S3, 19.2R2, so it looks safe — our inference, not a vendor statement

juniper-ptx1000 (environment) · juniper-ptx10001-36mr (environment) · juniper-ptx10002 (environment) · juniper-ptx10003 (environment) · juniper-ptx10004 (environment) · juniper-ptx10008 (environment) · juniper-ptx10016 (environment) · juniper-ptx3000 (environment) · juniper-ptx5000 (environment) · juniper-qfx10002 (environment) · juniper-qfx10008 (environment) · juniper-qfx10016 (environment) · juniper-qfx5100 (environment) · juniper-qfx5110 (environment) · juniper-qfx5120 (environment) · juniper-qfx5130 (environment) · juniper-qfx5200 (environment) · juniper-qfx5210 (environment) · juniper-qfx5220 (environment)

Ptx1000 · Juniperdevice

80%

All versions

Ptx10001-36Mr · Juniperdevice

80%

All versions

Ptx10002 · Juniperdevice

80%

All versions

Ptx10003 · Juniperdevice

80%

All versions