CVE-2021-0205: Junos OS: MX Series: Dynamic filter fails to match IPv6 prefix
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 19.1R2-S2, 19.1R3-S3 on MX Series; 19.2 versions prior to 19.2R3-S1 on MX Series; 19.3 versions prior to 19.3R2-S5, 19.3R3-S1 on MX Series; 19.4 versions prior to 19.4R3 on MX Series; 20.1 versions prior to 20.1R2 on MX Series; 20.2 versions prior to 20.2R2 on MX Series;
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Frequently Asked Questions
What is the severity of CVE-2021-0205?
CVE-2021-0205 has been classified as a medium severity vulnerability affecting certain versions of Juniper's JUNOS operating system.
How do I fix CVE-2021-0205?
To resolve CVE-2021-0205, upgrade Juniper JUNOS to a version that is not affected by this vulnerability, as detailed in the vendor's advisory.
Which Juniper products are affected by CVE-2021-0205?
CVE-2021-0205 affects Juniper Networks MX series devices configured with the Intrusion Detection Service feature using specific IPv6 settings.
What type of vulnerability is CVE-2021-0205?
CVE-2021-0205 is a configuration flaw where a dynamic firewall filter may misinterpret IPv6 prefixes, leading to unintended traffic blocking.
What is the impact of CVE-2021-0205?
The impact of CVE-2021-0205 is that it may cause legitimate IPv6 traffic to be mistakenly blocked, disrupting network functionality.