Junos OS: EX4300-MP/EX4600/EX4650/QFX5K Series: Packet Forwarding Engine manager (FXPC) process crashes when deployed in a Virtual Chassis (VC) configuration

Description

On Juniper Networks EX4300-MP Series, EX4600 Series, EX4650 Series, QFX5K Series deployed as a Virtual Chassis with a specific Layer 2 circuit configuration, Packet Forwarding Engine manager (FXPC) process may crash and restart upon receipt of specific layer 2 frames. Continued receipt and processing of this packet will create a sustained Denial of Service (DoS) condition. This issue affects: Juniper Networks Junos OS on EX4300-MP Series, EX4600 Series, EX4650 Series, QFX5K 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-S4, 17.4R3-S5; 18.2 versions prior to 18.2R3-S8; 18.3 versions prior to 18.3R3-S4; 18.4 versions prior to 18.4R2-S7, 18.4R3-S6; 19.1 versions prior to 19.1R3-S4; 19.2 versions prior to 19.2R1-S6, 19.2R3-S1; 19.3 versions prior to 19.3R3-S1; 19.4 versions prior to 19.4R2-S4, 19.4R3-S1; 20.1 versions prior to 20.1R2; 20.2 versions prior to 20.2R2, 20.2R3; 20.3 versions prior to 20.3R1-S2, 20.3R2;

Scores

EPSS (exploitation in 30 days)

0.38% · top 68% of all CVEs (6 Nov 2026)

The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 6.5.

Weakness

• 754 - Improper Check for Unusual or Exceptional Conditions
• Denial of Service (DoS)

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-S4, 17.4R3-S5
  • affected 18.2 – < 18.2R3-S8
  • affected 18.3 – < 18.3R3-S4
  • affected 18.4 – < 18.4R2-S7, 18.4R3-S6
  • affected 19.1 – < 19.1R3-S4
  • affected 19.2 – < 19.2R1-S6, 19.2R3-S1
  • affected 19.3 – < 19.3R3-S1
  • affected 19.4 – < 19.4R2-S4, 19.4R3-S1
  • affected 20.1 – < 20.1R2
  • affected 20.2 – < 20.2R2, 20.2R3
  • affected 20.3 – < 20.3R1-S2, 20.3R2

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-S4, 17.4R3-S5, 18.3R3-S4, 18.4R2-S7, 18.4R3-S6, 19.1R3-S4, 19.2R1-S6, 19.2R3-S1, 19.3R3-S1, 19.4R2-S4, 19.4R3-S1, 20.1R2, 20.2R2, 20.2R3, 20.3R1-S2, 20.3R2, 20.4R1, and all subsequent releases.

Workaround: There are no viable workarounds for this issue.

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

References (1)

• https://kb.juniper.net/JSA11132 (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-2021-0237](https://trackcve.app/badge/CVE-2021-0237.svg)](https://trackcve.app/cve/CVE-2021-0237)

Record last updated 17 Sept 2024, 02:56 UTC.