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             AUSCERT External Security Bulletin Redistribution

 JSA11049 - 2020-10 Security Bulletin: Junos OS: When a DHCPv6 Relay-Agent
          is configured upon receipt of a specific DHCPv6 client
         message, Remote Code Execution may occur. (CVE-2020-1656)
                              16 October 2020


        AusCERT Security Bulletin Summary

Product:           Junos OS
Publisher:         Juniper Networks
Operating System:  Juniper
Impact/Access:     Execute Arbitrary Code/Commands -- Remote/Unauthenticated
                   Denial of Service               -- Remote/Unauthenticated
Resolution:        Patch/Upgrade
CVE Names:         CVE-2020-1656  

Original Bulletin: 

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2020-10 Security Bulletin: Junos OS: When a DHCPv6 Relay-Agent is configured upon 
receipt of a specific DHCPv6 client message, Remote Code Execution may occur. (CVE-2020-1656)

Article ID  : JSA11049
Last Updated: 14 Oct 2020
Version     : 1.0

Product Affected:
This issue affects Junos OS 12.3, 12.3X48, 14.1X53, 15.1, 15.1X49, 15.1X53,
16.1, 16.2, 17.1, 17.2, 17.2X75, 17.3, 17.4, 18.1, 18.2, 18.2X75, 18.3, 18.4,
19.1, 19.2, 19.3.


The DHCPv6 Relay-Agent service, part of the Juniper Enhanced jdhcpd daemon
shipped with Juniper Networks Junos OS has an Improper Input Validation
vulnerability which will result in a Denial of Service (DoS) condition when a
DHCPv6 client sends a specific DHPCv6 message allowing an attacker to
potentially perform a Remote Code Execution (RCE) attack on the target device.

Continuous receipt of the specific DHCPv6 client message will result in an
extended Denial of Service (DoS) condition.

If adjacent devices are also configured to relay DHCP packets, and are not
affected by this issue and simply transparently forward unprocessed client
DHCPv6 messages, then the attack vector can be a Network-based attack, instead
of an Adjacent-device attack. No other DHCP services are affected. Receipt of
the packet without configuration of the DHCPv6 Relay-Agent service, will not
result in exploitability of this issue.

This issue affects Juniper Networks Junos OS:

  o 12.3 versions prior to 12.3R12-S15;
  o 12.3X48 versions prior to 12.3X48-D95;
  o 14.1X53 versions prior to 14.1X53-D53;
  o 15.1 versions prior to 15.1R7-S6;
  o 15.1X49 versions prior to 15.1X49-D200;
  o 15.1X53 versions prior to 15.1X53-D593;
  o 16.1 versions prior to 16.1R7-S7;
  o 16.2 versions prior to 16.2R2-S11;
  o 17.1 versions prior to 17.1R2-S11, 17.1R3-S2;
  o 17.2 versions prior to 17.2R3-S3;
  o 17.2X75 versions prior to 17.2X75-D44;
  o 17.3 versions prior to 17.3R3-S7;
  o 17.4 versions prior to 17.4R2-S9, 17.4R3;
  o 18.1 versions prior to 18.1R3-S9;
  o 18.2 versions prior to 18.2R2-S6, 18.2R3-S2;
  o 18.2X75 versions prior to 18.2X75-D12, 18.2X75-D33, 18.2X75-D435,
  o 18.3 versions prior to 18.3R1-S7, 18.3R2-S3, 18.3R3-S1;
  o 18.4 versions prior to 18.4R1-S5, 18.4R2-S3, 18.4R3;
  o 19.1 versions prior to 19.1R1-S4, 19.1R2;
  o 19.2 versions prior to 19.2R1-S3, 19.2R2;
  o 19.3 versions prior to 19.3R2.

The following minimal configuration is required:

[forwarding-options dhcp-relay dhcpv6]

More details on DHCPV6 Relay-Agent configuration and use are located in the
reference URLs.

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

This issue was seen during production usage.

This issue has been assigned CVE-2020-1656 .


The following software releases have been updated to resolve this specific
issue: Junos OS 12.3R12-S15, 12.3X48-D100, 12.3X48-D95, 14.1X53-D53, 15.1R7-S6,
15.1X49-D200, 15.1X53-D593, 16.1R7-S7, 16.2R2-S11, 17.1R2-S11, 17.1R3-S2,
17.2R3-S3, 17.2X75-D44, 17.3R3-S7, 17.4R2-S9, 17.4R3, 18.1R3-S9, 18.2R2-S6,
18.2R3-S2, 18.2X75-D12, 18.2X75-D33, 18.2X75-D435, 18.2X75-D60, 18.3R1-S7,
18.3R2-S3, 18.3R3-S1, 18.4R1-S5, 18.4R2-S3, 18.4R3, 19.1R1-S4, 19.1R2, 19.1R3,
19.2R1-S3, 19.2R2, 19.4R1, and all subsequent releases.

This issue is being tracked as 1461448 .


There are no available workarounds for this issue.

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

Modification History:
2020-10-14: Initial Publication.

CVSS Score:
8.8 (CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)

Severity Level:

Severity Assessment:
Information for how Juniper Networks uses CVSS can be found at KB 16446 "Common
Vulnerability Scoring System (CVSS) and Juniper's Security Advisories."

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