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6.5

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 caus...

CVE-2021-31366 · published 5 years ago
Summary

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 (A...

What to do

The CVE record does not list a fixed version. Check the vendor's site or the advisory links below - a fix may already be released.

Affected software
VendorProductAffected versions
juniper junos 15.1
17.3
17.4
18.1
18.2
18.3
18.4
19.1
19.2
19.3
19.4
20.1
4 more version ranges
cpe:2.3:o:juniper:junos:15.1:-:*:*:*:*:*:*
Original advisory text
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 caus...
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 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.
References
Fix within
Internet-facing 60 days
Internal At next upgrade
  • Not known to be exploited
  • Needs hands-on effort to exploit (estimated)
  • Gives an attacker partial control (estimated)
Severity
6.5 Medium
Exploitation
<1% chance of attack within 30 days
Type
CWE-252Unchecked Return Value
Timeline
Published19 Oct 2021
Updated4 Nov 2026
First seen29 Sep 2026
Sources
CVE-2021-31366 · NVD
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