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;

The examples of the config stanza affected by this issue:

Juniper SIRT is not aware of any malicious exploitation of this vulnerability.

This issue was found during internal product security testing or research.

This issue has been assigned CVE-2021-0227 .

The following software releases have been updated to resolve this specific issue: 17.3R3-S9, 17.4R2-S11, 17.4R3-S2, 18.2R3-S5, 18.3R2-S4, 18.3R3-S3, 18.4R2-S5, 18.4R3-S4, 19.1R3-S2, 19.2R1-S5, 19.2R3, 19.3R3, 19.4R2-S1, 19.4R3, 20.1R1-S2, 20.1R2, 20.2R1, and all subsequent releases.

This issue is being tracked as 1503557 .

Software releases or updates are available for download at https://support.juniper.net/support/downloads/

There are no viable workarounds for this issue.

To reduce the risk of exploitation of this issue, use access lists or firewall filters to limit access to only trusted administrative networks, hosts and users.

2021-04-14: Initial Publication.

• KB16613: Overview of the Juniper Networks SIRT Quarterly Security Bulletin Publication Process [juniper.net]
• KB16765: In which releases are vulnerabilities fixed? [juniper.net]
• KB16446: Common Vulnerability Scoring System (CVSS) and Juniper's Security Advisories [juniper.net]
• Report a Security Vulnerability - How to Contact the Juniper Networks Security Incident Response Team
• CVE-2021-0227 at cve.mitre.org