Time-of-check Time-of-use (TOCTOU) Race Condition in Juniper Junos OS - CVE-2021-0289
Published: July 15, 2021
Vulnerability identifier: #VU54915
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2021-0289
CWE-ID: CWE-367
Exploitation vector: Adjecent network
Exploit availability:
No public exploit available
Vendor: Juniper Networks, Inc.
Affected software:
Juniper Junos OS
Juniper Junos OS
Detailed vulnerability description
The vulnerability allows a remote attacker to bypass implemented security restrictions.
The vulnerability exists due to a race condition between the Device Control Daemon (DCD) and firewall process (dfwd) daemons of Juniper Networks Junos OS, when user-defined ARP Policer is configured and applied on one or more Aggregated Ethernet (AE) interface units. A remote attacker on the local network can bypass the user-defined ARP Policer.
How to mitigate CVE-2021-0289
Install updates from vendor's website.