Denial of service when handling BGP VPNv6 flowspec messages in Juniper Junos OS and OS Evolved

1) Improper Check for Unusual or Exceptional Conditions

EUVDB-ID: #VU52286

Risk: Medium

CVSSv4.0: 4.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2021-0236

CWE-ID: CWE-754 - Improper Check for Unusual or Exceptional Conditions

Exploit availability: No

Description

The vulnerability allows a remote user to perform denial of service attack.

The vulnerability exists due to improper check for unusual or exceptional conditions within the Routing Protocol Daemon (RPD) service when handling BGP VPNv6 flowspec messages. A remote user attacker can send specific matching BGP packet, which meets a specific term in the flowspec configuration and crash the service.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Juniper Junos OS: 18.4R1-S1 - 20.4

Junos OS Evolved: 20.3-EVO - 20.4

CPE2.3

• cpe:2.3:o:juniper_networks:juniper_junos_os:18.4:*:*:*:*:*:*:*
• cpe:2.3:o:juniper_networks:juniper_junos_os:19.1:*:*:*:*:*:*:*
• cpe:2.3:o:juniper_networks:juniper_junos_os:19.2:*:*:*:*:*:*:*
• cpe:2.3:o:juniper_networks:juniper_junos_os:19.3:*:*:*:*:*:*:*
• cpe:2.3:o:juniper_networks:juniper_junos_os:19.4:*:*:*:*:*:*:*
• cpe:2.3:o:juniper_networks:juniper_junos_os:20.1:*:*:*:*:*:*:*
• cpe:2.3:o:juniper_networks:juniper_junos_os:20.2:*:*:*:*:*:*:*
• cpe:2.3:o:juniper_networks:juniper_junos_os:20.3:*:*:*:*:*:*:*
• cpe:2.3:o:juniper_networks:juniper_junos_os:20.4:*:*:*:*:*:*:*
• cpe:2.3:o:juniper_networks:junos_os_evolved:20.3:*:*:*:*:*:*:*

External links

https://kb.juniper.net/InfoCenter/index?page=content&id=JSA11131&cat=SIRT_1&actp=LIST

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.