2021-10 Security Bulletin: Junos OS: MX Series: In subscriber management / BBE configuration authd can crash if a subscriber with a specific username tries to login leading to a DoS (CVE-2021-31366)

Product Affected

This issue affects all versions of Junos OS from 15.1 onwards. Affected platforms: MX Series

Severity

Medium

Severity Assessment (CVSS) Score

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

Problem

An Unchecked Return Value vulnerability in the authd (authentication daemon) of Juniper Networks Junos OS on MX Series configured for subscriber management / BBE allows an adjacent attacker to cause a crash by sending a specific username. This impacts authentication, authorization, and accounting (AAA) services on the MX devices and leads to a Denial of Service (DoS) condition.

Continued receipted of these PPP login request will create a sustained Denial of Service (DoS) condition.

This issue affects Juniper Networks Junos OS on MX Series:

15.1 versions prior to 15.1R7-S9;
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 18.4R3-S9;
19.1 versions prior to 19.1R3-S6;
19.2 versions prior to 19.2R1-S7, 19.2R3-S3;
19.3 versions prior to 19.3R2-S6, 19.3R3-S3;
19.4 versions prior to 19.4R3-S3;
20.1 versions prior to 20.1R3;
20.2 versions prior to 20.2R3-S1;
20.3 versions prior to 20.3R3;
20.4 versions prior to 20.4R3;
21.1 versions prior to 21.1R2.

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-2021-31366 .

Solution

The following software releases have been updated to resolve this specific issue: 15.1R7-S9, 17.3R3-S12, 17.4R3-S5, 18.1R3-S13, 18.2R3-S8, 18.3R3-S5, 18.4R3-S9, 19.1R3-S6, 19.2R1-S7, 19.2R3-S3, 19.3R2-S6, 19.3R3-S3, 19.4R3-S3, 20.1R3, 20.2R3-S1, 20.3R3, 20.4R3, 21.1R2, 21.2R1, and all subsequent releases.

This issue is being tracked as 1576182 .

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

Workaround

Please always configure a domain map none:

[access domain map none]

Severity Assessment

Information for how Juniper Networks uses CVSS can be found at KB 16446 [juniper.net] "Common Vulnerability Scoring System (CVSS) and Juniper's Security Advisories."

Modification History