CVE-2021-0227

Junos OS: SRX Series: Denial of Service in J-Web upon receipt of crafted HTTP packets

HIGH

7.5

CVSS Score

Published: April 22, 2021 at 07:36 PM UTC

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

22 products affected across 2 vendorsJunosSRX5600SRX5800

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Severity

HIGH7.5

Exploit prediction

EPSS 1%

Description

An improper restriction of operations within the bounds of a memory buffer vulnerability in Juniper Networks Junos OS J-Web on SRX Series devices allows an attacker to cause Denial of Service (DoS) by sending certain crafted HTTP packets. Continued receipt and processing of these packets will create a sustained Denial of Service (DoS) condition. When this issue occurs, web-management, NTP daemon (ntpd) and Layer 2 Control Protocol process (L2CPD) daemons might crash. This issue affects Juniper Networks Junos OS on SRX Series: 17.3 versions prior to 17.3R3-S9; 17.4 versions prior to 17.4R2-S11, 17.4R3-S2; 18.2 versions prior to 18.2R3-S5; 18.3 versions prior to 18.3R2-S4, 18.3R3-S3; 18.4 versions prior to 18.4R2-S5, 18.4R3-S4; 19.1 versions prior to 19.1R3-S2; 19.2 versions prior to 19.2R1-S5, 19.2R3; 19.3 versions prior to 19.3R3; 19.4 versions prior to 19.4R2-S1, 19.4R3; 20.1 versions prior to 20.1R1-S2, 20.1R2;

Affected

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

Junos · Juniper Networks

95%

17.3 ≤ v < 17.3R3-S917.4 ≤ v < 17.4R2-S11, 17.4R3-S218.2 ≤ v < 18.2R3-S518.3 ≤ v < 18.3R2-S4, 18.3R3-S318.4 ≤ v < 18.4R2-S5, 18.4R3-S419.1 ≤ v < 19.1R3-S219.2 ≤ v < 19.2R1-S5, 19.2R319.3 ≤ v < 19.3R319.4 ≤ v < 19.4R2-S1, 19.4R320.1 ≤ v < 20.1R1-S2, 20.1R217.3 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-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 17.4 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-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 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 18.3 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 r3 18.3 r3-s1 18.3 r3-s2 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 r3 18.4 r3-s1 18.4 r3-s2 18.4 r3-s3 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 r2 19.1 r2-s1 19.1 r3 19.1 r3-s1 19.2 19.2 r1 19.2 r1-s1 19.2 r1-s2 19.2 r1-s3 19.2 r1-s4 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 19.4 19.4 r1 19.4 r1-s1 19.4 r1-s2 19.4 r2 20.1 20.1 r1 20.1 r1-s1

Affected range stops below 17.3R3-S9, so it looks safe — our inference, not a vendor statement

Affected range stops below 17.4R2-S11, 17.4R3-S2, so it looks safe — our inference, not a vendor statement

Affected range stops below 18.2R3-S5, so it looks safe — our inference, not a vendor statement

Affected range stops below 18.3R2-S4, 18.3R3-S3, so it looks safe — our inference, not a vendor statement

Affected range stops below 18.4R2-S5, 18.4R3-S4, so it looks safe — our inference, not a vendor statement

Affected range stops below 19.1R3-S2, so it looks safe — our inference, not a vendor statement

Affected range stops below 19.2R1-S5, 19.2R3, so it looks safe — our inference, not a vendor statement

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

Affected range stops below 19.4R2-S1, 19.4R3, so it looks safe — our inference, not a vendor statement

Affected range stops below 20.1R1-S2, 20.1R2, so it looks safe — our inference, not a vendor statement

juniper-srx100 (environment) · juniper-srx110 (environment) · juniper-srx1400 (environment) · juniper-srx1500 (environment) · juniper-srx210 (environment) · juniper-srx220 (environment) · juniper-srx240 (environment) · juniper-srx300 (environment) · juniper-srx320 (environment) · juniper-srx340 (environment) · juniper-srx3400 (environment) · juniper-srx345 (environment) · juniper-srx3600 (environment) · juniper-srx4100 (environment) · juniper-srx4200 (environment) · juniper-srx4600 (environment) · juniper-srx5400 (environment) · juniper-srx550 (environment) · juniper-srx5600 (environment) · juniper-srx5800 (environment) · juniper-srx650 (environment)

SRX100 · Juniperdevice

80%

All versions

SRX110 · Juniperdevice

80%

All versions

SRX1400 · Juniperdevice

80%

All versions

Srx1500 · Juniperdevice

80%

All versions