CVE-2021-31364

/// Technical description

An Improper Check for Unusual or Exceptional Conditions vulnerability combined with a Race Condition in the flow daemon (flowd) of Juniper Networks Junos OS on SRX300 Series, SRX500 Series, SRX1500, and SRX5000 Series with SPC2 allows an unauthenticated network based attacker sending specific traffic to cause a crash of the flowd/srxpfe process, responsible for traffic forwarding in SRX, which will cause a Denial of Service (DoS). Continued receipt and processing of this specific traffic will create a sustained Denial of Service (DoS) condition. This issue can only occur when specific packets are trying to create the same session and logging for session-close is configured as a policy action. Affected platforms are: SRX300 Series, SRX500 Series, SRX1500, and SRX5000 Series with SPC2. Not affected platforms are: SRX4000 Series, SRX5000 Series with SPC3, and vSRX Series. This issue affects Juniper Networks Junos OS SRX300 Series, SRX500 Series, SRX1500, and SRX5000 Series with SPC2: All

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References