Operating System:

[Juniper]

Published:

30 October 2020

Protect yourself against future threats.

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             AUSCERT External Security Bulletin Redistribution

                               ESB-2020.3747
         Junos OS: EX4300 Series: High CPU load due to receipt of
                   specific IPv4 packets (CVE-2020-1670)
                              30 October 2020

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        AusCERT Security Bulletin Summary
        ---------------------------------

Product:           Junos OS
Publisher:         Juniper Networks
Operating System:  Juniper
Impact/Access:     Denial of Service -- Remote/Unauthenticated
Resolution:        Patch/Upgrade
CVE Names:         CVE-2020-1670  

Original Bulletin: 
   http://kb.juniper.net/InfoCenter/index?page=content&id=JSA11067&actp=RSS

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JSA11067 - 2020-10 Security Bulletin: Junos OS: EX4300 Series: High CPU load due
to receipt of specific IPv4 packets (CVE-2020-1670)  

PRODUCT AFFECTED:
This issue affects Junos OS 17.3, 17.4, 18.1, 18.2, 18.3, 18.4, 19.1, 19.2, 
19.3, 19.4, 20.1. Affected platforms: EX4300 series.

PROBLEM:
On Juniper Networks EX4300 Series, receipt of a stream of specific IPv4 packets
can cause Routing Engine (RE) high CPU load, which could lead to network protocol
operation issue and traffic interruption.

This specific packets can originate only from within the broadcast domain where
the device is connected.

This issue occurs when the packets enter to the IRB interface.

Only IPv4 packets can trigger this issue. IPv6 packets cannot trigger this issue.
 

This issue affects Juniper Networks Junos OS on EX4300 series:

17.3 versions prior to 17.3R3-S9;
17.4 versions prior to 17.4R2-S11, 17.4R3-S2;
18.1 versions prior to 18.1R3-S10;
18.2 versions prior to 18.2R3-S4;
18.3 versions prior to 18.3R2-S4, 18.3R3-S2;
18.4 versions prior to 18.4R2-S4, 18.4R3-S2;
19.1 versions prior to 19.1R2-S2, 19.1R3-S1;
19.2 versions prior to 19.2R1-S5, 19.2R2-S1, 19.2R3;
19.3 versions prior to 19.3R2-S4, 19.3R3;
19.4 versions prior to 19.4R1-S3, 19.4R2;
20.1 versions prior to 20.1R1-S3, 20.1R2.
 
The example of the configuration stanza affected by this issue is as follows:

[interfaces irb unit <UNIT_NUMBER>]
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-2020-1670.

SOLUTION:
The following software releases have been updated to resolve this specific issue:
17.3R3-S9, 17.4R2-S11, 17.4R3-S2, 18.1R3-S10, 18.2R3-S4, 18.3R2-S4, 18.3R3-S2, 
18.4R2-S4, 18.4R3-S2, 19.1R2-S2, 19.1R3-S1, 19.2R1-S5, 19.2R2-S1, 19.2R3, 
19.3R2-S4, 19.3R3, 19.4R1-S3, 19.4R2, 20.1R1-S3, 20.1R2, 20.2R1 and all 
subsequent releases.

This issue is being tracked as 1495129.

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

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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