On Juniper Networks Junos OS platforms configured as DHCPv6 local server or DHCPv6 Relay Agent, Juniper Networks Dynamic Host Configuration Protocol Daemon (JDHCPD) process might crash with a core dump if a malformed or specific DHCPv6 packet is received, resulting in a restart of the daemon. The daemon automatically restarts without intervention, but continued receipt and processing of these packets will repeatedly crash the JDHCPD process and sustain the Denial of Service (DoS) condition.

These issues only affect DHCPv6. DHCPv4 is not affected by these issues.

These issues affect Juniper Networks Junos OS:

• 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 18.4R1-S8, 18.4R3-S7;
• 19.1 versions prior to 19.1R3-S5;
• 19.2 versions prior to 19.2R3-S2;
• 19.3 versions prior to 19.3R3-S2;
• 19.4 versions prior to 19.4R3-S2;
• 20.1 versions prior to 20.1R3;
• 20.2 versions prior to 20.2R2-S3, 20.2R3;
• 20.3 versions prior to 20.3R2;
• 20.4 versions prior to 20.4R2.

The example of DHCPv6 local server configuration stanza affected by this issue is:

The example of configuration stanza for DHCPv6 Relay Agent affected by this issue is:

These issues were seen during production usage.

The following software releases have been updated to resolve these specific issues: Junos OS 17.3R3-S12, 17.4R3-S5, 18.1R3-S13, 18.2R3-S8, 18.3R3-S5, 18.4R1-S8, 18.4R3-S7, 19.1R3-S5, 19.2R3-S2, 19.3R3-S2, 19.4R3-S2, 20.1R3, 20.2R2-S3, 20.2R3, 20.3R2, 20.4R2, 21.1R1, and all subsequent releases.

This issue is being tracked as  1564434  and  1546166 .
 

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

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-2021-0240 at cve.mitre.org
• CVE-2021-0241 at cve.mitre.org