CVE-2021-31368

Junos OS: EX2300 Series, EX3400 Series, and ACX710 might become unresponsive if the out-of-band management port receives a flood of traffic

HIGH

7.5

CVSS Score

Published: October 19, 2021 at 06:16 PM UTC

Updated: June 17, 2026 at 03:51 AM UTC

6 products affected across 2 vendorsJunosEx2300Ex3400

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Severity

HIGH7.5

Exploit prediction

EPSS 1%

Description

An Uncontrolled Resource Consumption vulnerability in the kernel of Juniper Networks JUNOS OS allows an unauthenticated network based attacker to cause 100% CPU load and the device to become unresponsive by sending a flood of traffic to the out-of-band management ethernet port. Continued receipted of a flood will create a sustained Denial of Service (DoS) condition. Once the flood subsides the system will recover by itself. An indication that the system is affected by this issue would be that kernel and netisr process are shown to be using a lot of CPU cycles like in the following example output: user@host> show system processes extensive ... PID USERNAME PRI NICE SIZE RES STATE C TIME WCPU COMMAND 16 root -72 - 0K 304K WAIT 1 839:40 88.96% intr{swi1: netisr 0} 0 root 97 - 0K 160K RUN 1 732:43 87.99% kernel{bcm560xgmac0 que} This issue affects Juniper Networks JUNOS OS on EX2300 Series, EX3400 Series, and ACX710: All versions prior to 18.1R3-S13; 18.2 versions prior to 18.2R3-S8; 18.3 versions prior to 18.3R3-S5; 18.4 versions prior to 18.4R2-S8, 18.4R3-S9; 19.1 versions prior to 19.1R3-S5; 19.2 versions prior to 19.2R1-S7, 19.2R3-S3; 19.3 versions prior to 19.3R2-S6, 19.3R3-S2; 19.4 versions prior to 19.4R1-S4, 19.4R3-S3; 20.1 versions prior to 20.1R2-S2, 20.1R3; 20.2 versions prior to 20.2R3; 20.3 versions prior to 20.3R2-S1, 20.3R3; 20.4 versions prior to 20.4R2.

Affected

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

Junos · Juniper Networks

95%

v < 18.1v < 18.1R3-S1318.2 ≤ v < 18.2R3-S818.3 ≤ v < 18.3R3-S518.4 ≤ v < 18.4R2-S8, 18.4R3-S919.1 ≤ v < 19.1R3-S519.2 ≤ v < 19.2R1-S7, 19.2R3-S319.3 ≤ v < 19.3R2-S6, 19.3R3-S219.4 ≤ v < 19.4R1-S4, 19.4R3-S320.1 ≤ v < 20.1R2-S2, 20.1R320.2 ≤ v < 20.2R320.3 ≤ v < 20.3R2-S1, 20.3R320.4 ≤ v < 20.4R218.1 18.1 r 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-s12 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 18.1 r3-s9 18.2 18.2 r 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 r2-s6 18.2 r2-s7 18.2 r2-s8 18.2 r3 18.2 r3-s1 18.2 r3-s2 18.2 r3-s3 18.2 r3-s4 18.2 r3-s5 18.2 r3-s6 18.2 r3-s7 18.3 18.3 r 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 r2 18.3 r2-s1 18.3 r2-s2 18.3 r2-s3 18.3 r2-s4 18.3 r3 18.3 r3-s1 18.3 r3-s2 18.3 r3-s3 18.3 r3-s4 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 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 19.1 19.1 r1 19.1 r1-s1 19.1 r1-s2 19.1 r1-s3 19.1 r1-s4 19.1 r1-s5 19.1 r1-s6 19.1 r2 19.1 r2-s1 19.1 r2-s2 19.1 r2-s3 19.1 r3 19.1 r3-s1 19.1 r3-s2 19.1 r3-s3 19.1 r3-s4 19.2 19.2 r1 19.2 r1-s1 19.2 r1-s2 19.2 r1-s3 19.2 r1-s4 19.2 r1-s5 19.2 r1-s6 19.2 r2 19.2 r2-s1 19.2 r3 19.2 r3-s1 19.2 r3-s2 19.3 19.3 r1 19.3 r1-s1 19.3 r2 19.3 r2-s1 19.3 r2-s2 19.3 r2-s3 19.3 r2-s4 19.3 r2-s5 19.3 r3 19.3 r3-s1 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 r2-s4 19.4 r2-s5 19.4 r3 19.4 r3-s1 19.4 r3-s2 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 20.3 20.3 r1 20.3 r1-s1 20.3 r2 20.4 20.4 r1 20.4 r1-s1

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

Affected range stops below 18.1R3-S13, so it looks safe — our inference, not a vendor statement

Affected range stops below 18.2R3-S8, so it looks safe — our inference, not a vendor statement

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

Affected range stops below 18.4R2-S8, 18.4R3-S9, so it looks safe — our inference, not a vendor statement

Affected range stops below 19.1R3-S5, so it looks safe — our inference, not a vendor statement

Affected range stops below 19.2R1-S7, 19.2R3-S3, so it looks safe — our inference, not a vendor statement

Affected range stops below 19.3R2-S6, 19.3R3-S2, so it looks safe — our inference, not a vendor statement

Affected range stops below 19.4R1-S4, 19.4R3-S3, so it looks safe — our inference, not a vendor statement

Affected range stops below 20.1R2-S2, 20.1R3, so it looks safe — our inference, not a vendor statement

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

Affected range stops below 20.3R2-S1, 20.3R3, so it looks safe — our inference, not a vendor statement

Affected range stops below 20.4R2, so it looks safe — our inference, not a vendor statement

juniper-acx710 (environment) · juniper-ex2300 (environment) · juniper-ex2300-c (environment) · juniper-ex2300m (environment) · juniper-ex3400 (environment)

Acx710 · Juniperdevice

80%

All versions

Ex2300 · Juniperdevice

80%

All versions

Ex2300-C · Juniperdevice

80%

All versions

Ex2300M · Juniperdevice

80%

All versions