Junos OS: QFX5000 Series and EX4600 Series: Continuous traffic destined to a device configured with MC-LAG leading to nodes losing their control connection which can impact traffic

Description

An uncontrolled resource consumption vulnerability in Juniper Networks Junos OS on QFX5000 Series and EX4600 Series switches allows an attacker sending large amounts of legitimate traffic destined to the device to cause Interchassis Control Protocol (ICCP) interruptions, leading to an unstable control connection between the Multi-Chassis Link Aggregation Group (MC-LAG) nodes which can in turn lead to traffic loss. Continued receipt of this amount of traffic will create a sustained Denial of Service (DoS) condition. An indication that the system could be impacted by this issue is the following log message: "DDOS_PROTOCOL_VIOLATION_SET: Warning: Host-bound traffic for protocol/exception LOCALNH:aggregate exceeded its allowed bandwidth at fpc <fpc number> for <n> times, started at <timestamp>" This issue affects Juniper Networks Junos OS on QFX5000 Series and EX4600 Series: 15.1 versions prior to 15.1R7-S9; 17.3 versions prior to 17.3R3-S11; 17.4 versions prior to 17.4R2-S13, 17.4R3-S5; 18.3 versions prior to 18.3R3-S5; 18.4 versions prior to 18.4R2-S8, 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 19.3R2-S6, 19.3R3-S2; 19.4 versions prior to 19.4R1-S4, 19.4R2-S4, 19.4R3-S2; 20.1 versions prior to 20.1R2-S2, 20.1R3; 20.2 versions prior to 20.2R2-S3, 20.2R3; 20.3 versions prior to 20.3R2; 20.4 versions prior to 20.4R1-S1, 20.4R2.

Timeline

Scores

EPSS (exploitation in 30 days)

0.96% · top 38% of all CVEs (7 Nov 2026)

The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.5.

Weakness

• CWE-770 Allocation of Resources Without Limits or Throttling (opens in a new tab)All about CWE-770 and its CVEs
• CWE-400 (opens in a new tab)All about CWE-400 and its CVEs

Affected products

• Juniper Networks · Junos OS

  • affected 15.1 – < 15.1R7-S9
  • affected 17.3 – < 17.3R3-S11
  • affected 17.4 – < 17.4R2-S13, 17.4R3-S5
  • affected 18.3 – < 18.3R3-S5
  • affected 18.4 – < 18.4R2-S8, 18.4R3-S7
  • affected 19.1 – < 19.1R3-S5
  • affected 19.2 – < 19.2R1-S6, 19.2R3-S2
  • affected 19.3 – < 19.3R2-S6, 19.3R3-S2
  • affected 19.4 – < 19.4R1-S4, 19.4R2-S4, 19.4R3-S2
  • affected 20.1 – < 20.1R2-S2, 20.1R3
  • affected 20.2 – < 20.2R2-S3, 20.2R3
  • affected 20.3 – < 20.3R2
  • affected 20.4 – < 20.4R1-S1, 20.4R2

What to do

Solution: The following software releases have been updated to resolve this specific issue: 15.1R7-S9, 17.3R3-S11, 17.4R2-S13, 17.4R3-S5, 18.1R3-S13, 18.2R3-S8, 18.3R3-S5, 18.4R2-S8, 18.4R3-S7, 19.1R3-S5, 19.2R1-S6, 19.2R3-S2, 19.3R2-S6, 19.3R3-S2, 19.4R1-S4, 19.4R2-S4, 19.4R3-S2, 20.1R2-S2, 20.1R3, 20.2R2-S3, 20.2R3, 20.3R2, 20.4R1-S1, 20.4R2, 21.1R1, and all subsequent releases.

Workaround: While no complete workaround exists, the risk of malicious exploitation can be reduced by filtering undesirable traffic using firewall filters and policers, or increase the bandwidth for the localnh DDOS queue.

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

References (1)

• https://kb.juniper.net/JSA11187 (opens in a new tab)x_refsource_CONFIRMx_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-2021-0285](https://trackcve.app/badge/CVE-2021-0285.svg)](https://trackcve.app/cve/CVE-2021-0285)

Record last updated 16 Sept 2024, 16:33 UTC.