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Fencer Vulns
high 7.4

CVE-2021-0222 json

Junos OS: Upon receipt of certain protocol packets with invalid payloads a self-propagating Denial of Service may occur.

published 2021-01-15 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-2841

cvss
7.4
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 51%
public exploits
0
none known

Summary

A vulnerability in Juniper Networks Junos OS allows an attacker to cause a Denial of Service (DoS) to the device by sending certain crafted protocol packets from an adjacent device with invalid payloads to the device. These crafted packets, which should be discarded, are instead replicated and sent to the RE. Over time, a Denial of Service (DoS) occurs. Continued receipt of these crafted protocol packets will cause an extended Denial of Service (DoS) condition, which may cause wider traffic impact due to protocol flapping. An indication of compromise is to check "monitor interface traffic" on the ingress and egress port packet counts. For each ingress packet, two duplicate packets are seen on egress. This issue can be triggered by IPv4 and IPv6 packets. This issue affects all traffic through the device. This issue affects: Juniper Networks Junos OS: 14.1X53 versions prior to 14.1X53-D53 on EX4300, QFX3500, QFX5100, EX4600; 15.1 versions prior to 15.1R7-S6 on EX4300, QFX3500, QFX5100, EX4600; 16.1 versions prior to 16.1R7-S7 on EX4300, QFX5100, EX4600; 17.1 versions prior to 17.1R2-S11 on EX4300, QFX5100, EX4600; 17.1 versions prior to 117.1R3-S2 on EX4300; 17.2 versions prior to 17.2R1-S9 on EX4300; 17.2 versions prior to 17.2R3-S3 on EX4300, QFX5100, EX4600, QFX5110, QFX5200; 17.3 versions prior to 17.3R2-S5, 17.3R3-S7 on EX4300, QFX5100, EX4600, QFX5110, QFX5200; 17.4 versions prior to 17.4R2-S9, 17.4R3 on EX4300, QFX5100, EX4600, QFX5110, QFX5200; 18.1 versions prior to 18.1R3-S9 on EX4300, QFX5100, EX4600, QFX5110, QFX5200, QFX5210, EX2300, EX3400; 18.2 versions prior to 18.2R2-S7 on EX4300; 18.2 versions prior to 18.2R3-S3 on EX4300, QFX5100, EX4600, QFX5110, QFX5200, QFX5210, EX2300, EX3400; 18.3 versions prior to 18.3R2-S3, on EX4300; 18.3 versions prior to 18.3R1-S7, 18.3R3-S1 on EX4300, QFX5100, EX4600, QFX5110, QFX5200, QFX5210, QFX5120, EX4650, EX2300, EX3400; 18.4 versions prior to 18.4R1-S5, 18.4R2-S3, 18.4R3 on EX4300, QFX5100, EX4600, QFX5110, QFX5200, QFX5210, QFX5120, EX4650, EX2300, EX3400; 19.1 versions prior to 19.1R1-S4, 19.1R2-S1, 19.1R3 on EX4300, QFX5100, EX4600, QFX5110, QFX5200, QFX5210, QFX5120, EX4650, EX2300, EX3400; 19.2 versions prior to 19.2R1-S4, 19.2R2 on EX4300; 19.2 versions prior to 19.2R1-S3, 19.2R2 on QFX5100, EX4600, QFX5110, QFX5200, QFX5210, QFX5120, EX4650, EX2300, EX3400; 19.3 versions prior to 19.3R2-S1, 19.3R3 on EX4300; 19.3 versions prior to 19.3R1-S1, 19.3R2, 19.3R3 on QFX5100, EX4600, QFX5110, QFX5200, QFX5210, QFX5120, EX4650, EX2300, EX3400;

Patch / fix

  • Juniper Networks Junos OS 14.1X53-D53, 15.1R7-S6, 16.1R7-S7, 17.1R2-S11, 17.1R3-S2, 17.2R1-S9, 17.2R3-S3, 17.3R2-S5, 17.3R3-S7, 17.4R2-S9, 17.4R3, 18.1R3-S9, 18.2R2-S7, 18.2R3-S3, 18.3R1-S7, 18.3R3-S1, 18.3R2-S3, 18.4R1-S5, 18.4R2-S3, 18.4R3, 19.1R1-S4, 19.1R2-S1, 19.1R3, 19.2R1-S3, 19.2R2, 19.2R1-S4, 19.2R2, 19.3R1-S1, 19.3R2, 19.3R3, 19.3R2-S1, 19.3R3

Exploit prediction

0.65% chance of exploitation in the next 30 days, higher than 51% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.4 CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
NVD 2.0 6.1 AV:A/AC:L/Au:N/C:N/I:N/A:C

Affected products

  • Juniper Networks Junos OS

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.