Junos OS: Receipt of specific packets could lead to Denial of Service in MQTT Server

Description

An uncontrolled resource consumption vulnerability in Message Queue Telemetry Transport (MQTT) server of Juniper Networks Junos OS allows an attacker to cause MQTT server to crash and restart leading to a Denial of Service (DoS) by sending a stream of specific packets. A Juniper Extension Toolkit (JET) application designed with a listening port uses the Message Queue Telemetry Transport (MQTT) protocol to connect to a mosquitto broker that is running on Junos OS to subscribe for events. Continued receipt and processing of this packet will create a sustained Denial of Service (DoS) condition. This issue affects Juniper Networks Junos OS: 16.1R1 and later versions prior to 17.3R3-S11; 17.4 versions prior to 17.4R2-S13, 17.4R3-S4; 18.1 versions prior to 18.1R3-S12; 18.2 versions prior to 18.2R2-S8, 18.2R3-S7; 18.3 versions prior to 18.3R3-S4; 18.4 versions prior to 18.4R1-S8, 18.4R2-S7, 18.4R3-S7; 19.1 versions prior to 19.1R3-S5; 19.2 versions prior to 19.2R1-S6, 19.2R3-S2; 19.3 versions prior to 19.3R3-S2; 19.4 versions prior to 19.4R2-S4, 19.4R3-S2; 20.1 versions prior to 20.1R2-S1, 20.1R3; 20.2 versions prior to 20.2R2-S2, 20.2R3; 20.3 versions prior to 20.3R1-S1, 20.3R2. This issue does not affect Juniper Networks Junos OS versions prior to 16.1R1.

Timeline

Scores

EPSS (exploitation in 30 days)

1.2% · top 33% of all CVEs (7 Nov 2026)

The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.3.

Weakness

• CWE-400 Uncontrolled Resource Consumption (opens in a new tab)All about CWE-400 and its CVEs
• Denial of Service (DoS)

Affected products

• Juniper Networks · Junos OS

  • affected 16.1R1 – < 16.1*
  • affected 17.3 – < 17.3R3-S11
  • affected 17.4 – < 17.4R2-S13, 17.4R3-S4
  • affected 18.1 – < 18.1R3-S12
  • affected 18.2 – < 18.2R2-S8, 18.2R3-S7
  • affected 18.3 – < 18.3R3-S4
  • affected 18.4 – < 18.4R1-S8, 18.4R2-S7, 18.4R3-S7
  • affected 19.1 – < 19.1R3-S5
  • affected 19.2 – < 19.2R1-S6, 19.2R3-S2
  • affected 19.3 – < 19.3R3-S2
  • affected 19.4 – < 19.4R2-S4, 19.4R3-S2
  • affected 20.1 – < 20.1R2-S1, 20.1R3
  • affected 20.2 – < 20.2R2-S2, 20.2R3
  • affected 20.3 – < 20.3R1-S1, 20.3R2

What to do

Solution: The following software releases have been updated to resolve this specific issue: Junos OS: 17.3R3-S11, 17.4R2-S13, 17.4R3-S4, 18.1R3-S12, 18.2R2-S8, 18.2R3-S7, 18.3R3-S4, 18.4R1-S8, 18.4R2-S7, 18.4R3-S7, 19.1R3-S5, 19.2R1-S6, 19.2R3-S2, 19.3R3-S2, 19.4R2-S4, 19.4R3-S2, 20.1R2-S1, 20.1R3, 20.2R2-S2, 20.2R3, 20.3R1-S1, 20.3R2, 20.4R1, and all subsequent releases.

Workaround: There are no viable workarounds for this issue. To reduce the risk of exploitation utilize common security BCPs to limit the exploitable surface by limiting access to network and device to trusted systems, administrators, networks and hosts.

Exploitation: Juniper SIRT is not aware of any malicious exploitation of this vulnerability.

References (1)

• https://kb.juniper.net/JSA11124 (opens in a new tab)x_refsource_MISCx_transferred

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2021-0229](https://trackcve.app/badge/CVE-2021-0229.svg)](https://trackcve.app/cve/CVE-2021-0229)

Record last updated 16 Sept 2024, 18:08 UTC.