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2020-10 Security Bulletin: Junos OS: jdhcpd process crash when forwarding a malformed DHCP packet. (CVE-2020-1661)

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Article ID: JSA11056 SECURITY_ADVISORIES Last Updated: 29 Oct 2020Version: 2.0
Product Affected:
This issue affects Junos OS 12.3, 12.3X48, 14.1X53, 15.1, 15.1X49, 15.1X53, 16.1.
Problem:

On Juniper Networks Junos OS devices configured as a DHCP forwarder, the Juniper Networks Dynamic Host Configuration Protocol Daemon (jdhcp) process might crash when receiving a malformed DHCP packet.

This issue only affects devices configured as DHCP forwarder with forward-only option, that forward specified DHCP client packets, without creating a new subscriber session.

The jdhcpd daemon automatically restarts without intervention, but continuous receipt of the malformed DHCP packet will repeatedly crash jdhcpd, leading to an extended Denial of Service (DoS) condition.

This issue can be triggered only by DHCPv4, it cannot be triggered by DHCPv6.
 

This issue affects Juniper Networks Junos OS:

  • 12.3 versions prior to 12.3R12-S16;
  • 12.3X48 versions prior to 12.3X48-D105 on SRX Series;
  • 14.1X53 versions prior to 14.1X53-D60 on EX and QFX Series;
  • 15.1 versions prior to 15.1R7-S7;
  • 15.1X49 versions prior to 15.1X49-D221, 15.1X49-D230 on SRX Series;
  • 15.1X53 versions prior to 15.1X53-D593 on EX2300/EX3400;
  • 16.1 versions prior to 16.1R7-S5.
     

The examples of the config stanza affected by this issue:

[forwarding-options dhcp-relay forward-only]

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-2020-1661.

Solution:

The following software releases have been updated to resolve this specific issue: Junos OS 12.3R12-S16, 12.3X48-D105, 15.1R7-S7, 15.1X49-D221, 15.1X49-D230, 15.1X53-D593, 16.1R7-S5, 16.2R1 and all subsequent releases.

This issue is being tracked as 1430874.

Workaround:
There are no viable workarounds for this issue.
Implementation:
Software releases or updates are available for download at https://www.juniper.net/support/downloads/.
Modification History:
2020-10-14: Initial Publication.
CVSS Score:
5.3 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L)
Severity Level:
Medium
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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