2021-01 Security Bulletin: Junos OS and Junos OS Evolved: Upon receipt of a specific BGP FlowSpec message network traffic may be disrupted. (CVE-2021-0211)

Product Affected:

This issue affects Junos OS 15.1, 15.1X49, 17.3, 17.4, 18.1, 18.2, 18.3, 18.4, 19.1, 19.2, 19.3, 19.4, 20.1, 20.2, 20.3. This issue affects Junos OS Evolved 20.3.

Problem:

An improper check for unusual or exceptional conditions in Juniper Networks Junos OS and Junos OS Evolved Routing Protocol Daemon (RPD) service allows an attacker to send a valid BGP FlowSpec message thereby causing an unexpected change in the route advertisements within the BGP FlowSpec domain leading to disruptions in network traffic causing a Denial of Service (DoS) condition.

Continued receipt of these update messages will cause a sustained Denial of Service condition.

This issue affects Juniper Networks:

Junos OS:

All versions prior to 17.3R3-S10 with the exceptions of 15.1X49-D240 on SRX Series and 15.1R7-S8 on EX Series;
17.4 versions prior to 17.4R2-S12, 17.4R3-S4;
18.1 versions prior to 18.1R3-S12;
18.2 versions prior to 18.2R2-S8, 18.2R3-S6;
18.3 versions prior to 18.3R3-S4;
18.4 versions prior to 18.4R1-S8, 18.4R2-S6, 18.4R3-S6;
19.1 versions prior to 19.1R1-S6, 19.1R2-S2, 19.1R3-S3;
19.2 versions prior to 19.2R3-S1;
19.3 versions prior to 19.3R2-S5, 19.3R3-S1;
19.4 versions prior to 19.4R1-S3, 19.4R2-S3, 19.4R3;
20.1 versions prior to 20.1R2;
20.2 versions prior to 20.2R1-S3 20.2R2;
20.3 versions prior to 20.3R1-S1, 20.3R2.

Junos OS Evolved:

All versions prior to 20.3R1-S1-EVO, 20.3R2-EVO.

The following minimal configuration is required to potentially hit this issue:

protocols bgp family inet flow

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-2021-0211.

Solution:

The following software releases have been updated to resolve this specific issue:

Junos OS: 15.1R7-S8, 15.1X49-D240, 17.3R3-S10, 17.4R2-S12, 17.4R3-S4, 18.1R3-S12, 18.2R2-S8, 18.2R3-S6, 18.3R3-S4, 18.4R1-S8, 18.4R2-S6, 18.4R3-S6, 19.1R2-S2, 19.1R3-S3, 19.2R3-S1, 19.3R2-S5, 19.3R3-S1, 19.4R1-S3, 19.4R2-S3, 19.4R3, 20.1R2, 20.2R1-S3, 20.2R2, 20.3R1-S1, 20.3R2, 20.4R1, and all subsequent releases.

Junos OS Evolved: 20.3R1-S1-EVO, 20.3R2-EVO, 20.4R1-EVO, and all subsequent releases.

This issue is being tracked as 1539109.

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:

2021-01-13: Initial Publication.

2021-01-13: Added 15.1R7-S8 as fix point for EX Series which are affected.

CVSS Score:

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

Severity Level:

Critical

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."

Knowledge Base