CVE-2021-31366

Junos OS: MX Series: In subscriber management / BBE configuration authd can crash if a subscriber with a specific username tries to login leading to a DoS

MEDIUM

6.5

CVSS Score

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

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

17 products affected across 2 vendorsJunosMx960Mx480

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Severity

MEDIUM6.5

Exploit prediction

EPSS 0.4%

Description

An Unchecked Return Value vulnerability in the authd (authentication daemon) of Juniper Networks Junos OS on MX Series configured for subscriber management / BBE allows an adjacent attacker to cause a crash by sending a specific username. This impacts authentication, authorization, and accounting (AAA) services on the MX devices and leads to a Denial of Service (DoS) condition. Continued receipted of these PPP login request will create a sustained Denial of Service (DoS) condition. This issue affects: Juniper Networks Junos OS 15.1 versions prior to 15.1R7-S9; 17.3 versions prior to 17.3R3-S12; 17.4 versions prior to 17.4R3-S5; 18.1 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 18.4R3-S9; 19.1 versions prior to 19.1R3-S6; 19.2 versions prior to 19.2R1-S7, 19.2R3-S3; 19.3 versions prior to 19.3R2-S6, 19.3R3-S3; 19.4 versions prior to 19.4R3-S3; 20.1 versions prior to 20.1R3; 20.2 versions prior to 20.2R3-S1; 20.3 versions prior to 20.3R3; 20.4 versions prior to 20.4R3; 21.1 versions prior to 21.1R2.

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-S917.3 ≤ v < 17.3R3-S1217.4 ≤ v < 17.4R3-S518.1 ≤ v < 18.1R3-S1318.2 ≤ v < 18.2R3-S818.3 ≤ v < 18.3R3-S518.4 ≤ v < 18.4R3-S919.1 ≤ v < 19.1R3-S619.2 ≤ v < 19.2R1-S7, 19.2R3-S319.3 ≤ v < 19.3R2-S6, 19.3R3-S319.4 ≤ v < 19.4R3-S320.1 ≤ v < 20.1R320.2 ≤ v < 20.2R3-S120.3 ≤ v < 20.3R320.4 ≤ v < 20.4R321.1 ≤ v < 21.1R215.1 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 15.1 r7-s6 15.1 r7-s7 15.1 r7-s8 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 r2-s5 17.3 r3 17.3 r3-s1 17.3 r3-s10 17.3 r3-s11 17.3 r3-s2 17.3 r3-s3 17.3 r3-s4 17.3 r3-s5 17.3 r3-s6 17.3 r3-s7 17.3 r3-s8 17.3 r3-s9 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-s12 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 17.4 r2-s9 17.4 r3 17.4 r3-s1 17.4 r3-s2 17.4 r3-s3 17.4 r3-s4 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-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 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 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 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 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 19.1 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 r3 19.1 r3-s1 19.1 r3-s2 19.1 r3-s3 19.1 r3-s4 19.1 r3-s5 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 r3-s3 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-s3 19.4 19.4 r1 19.4 r1-s1 19.4 r1-s2 19.4 r1-s3 19.4 r1-s4 19.4 r2 19.4 r2-s1 19.4 r2-s2 19.4 r2-s3 19.4 r2-s4 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 20.1 r2-s2 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 20.3 20.3 r1 20.3 r1-s1 20.3 r2 20.3 r2-s1 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

Affected range stops below 15.1R7-S9, so it looks safe — our inference, not a vendor statement

Affected range stops below 17.3R3-S12, so it looks safe — our inference, not a vendor statement

Affected range stops below 17.4R3-S5, 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 18.4R3-S9, so it looks safe — our inference, not a vendor statement

Affected range stops below 19.1R3-S6, 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-S3, 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

Affected range stops below 20.2R3-S1, so it looks safe — our inference, not a vendor statement

Affected range stops below 20.3R3, 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

juniper-mx10 (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)

Mx10 · Juniperdevice

80%

All versions

Mx10003 · Juniperdevice

80%

All versions

Mx10008 · Juniperdevice

80%

All versions

Mx10016 · Juniperdevice

80%

All versions