CVE detail

CVE-2021-0205 — CVE-2021-0205

Published 2021-01-15 · Modified 2026-06-17 · Vendor juniper · Product junos · Source nvd
MEDIUM
severity
CVSS-derived band
5.8
CVSS v3
0–10 scale
0.0120
EPSS probability
exploitation probability, 30d
65.0%
EPSS percentile
percentile vs all CVEs
NOT LISTED
CISA KEV
known exploited catalog

Description

When the "Intrusion Detection Service" (IDS) feature is configured on Juniper Networks MX series with a dynamic firewall filter using IPv6 source or destination prefix, it may incorrectly match the prefix as /32, causing the filter to block unexpected traffic. This issue affects only IPv6 prefixes when used as source and destination. This issue affects MX Series devices using MS-MPC, MS-MIC or MS-SPC3 service cards with IDS service configured. This issue affects: Juniper Networks Junos OS 17.3 versions prior to 17.3R3-S10 on MX Series; 17.4 versions prior to 17.4R3-S3 on MX Series; 18.1 versions prior to 18.1R3-S11 on MX Series; 18.2 versions prior to 18.2R3-S6 on MX Series; 18.3 versions prior to 18.3R3-S4 on MX Series; 18.4 versions prior to 18.4R3-S6 on MX Series; 19.1 versions prior to

Remediation

vendor remediation guidance

The following software releases have been updated to resolve this specific issue: Junos OS: 17.3R3-S10, 17.4R3-S3, 18.1R3-S11, 18.2R3-S6, 18.3R3-S4, 18.4R3-S6, 19.1R2-S2, 19.1R3-S3, 19.2R3-S1, 19.3R2-S5, 19.3R3-S1, 19.4R3, 20.1R2, 20.2R2, 20.3R1 and all subsequent releases.

workarounds

IDS configuration can be disabled.

ProductVulnerable rangeFixed versionAdvisory
Juniper Networks Junos OS>=17.3<17.3R3-S1017.3R3-S10advisory ↗
Juniper Networks Junos OS>=17.4<17.4R3-S317.4R3-S3advisory ↗
Juniper Networks Junos OS>=18.1<18.1R3-S1118.1R3-S11advisory ↗
Juniper Networks Junos OS>=18.2<18.2R3-S618.2R3-S6advisory ↗
Juniper Networks Junos OS>=18.3<18.3R3-S418.3R3-S4advisory ↗
Juniper Networks Junos OS>=18.4<18.4R3-S618.4R3-S6advisory ↗
Juniper Networks Junos OS>=19.1<19.1R2-S2, 19.1R3-S319.1R2-S2, 19.1R3-S3advisory ↗
Juniper Networks Junos OS>=19.2<19.2R3-S119.2R3-S1advisory ↗
Juniper Networks Junos OS>=19.3<19.3R2-S5, 19.3R3-S119.3R2-S5, 19.3R3-S1advisory ↗
Juniper Networks Junos OS>=19.4<19.4R319.4R3advisory ↗
Juniper Networks Junos OS>=20.1<20.1R220.1R2advisory ↗
Juniper Networks Junos OS>=20.2<20.2R220.2R2advisory ↗

References

cvedb.io · NVD · CISA KEV · FIRST EPSS · vendor advisories (CVE Program List v5). Informational only, no warranty — verify every remediation against the vendor advisory before acting on it. This product uses data from the NVD API but is not endorsed or certified by the NVD, CISA, FIRST.org or any vendor named. CVE® is a registered trademark of The MITRE Corporation.