CVE-2021-0271 in Junos OS
Summary
by MITRE • 04/23/2021
A Double Free vulnerability in the software forwarding interface daemon (sfid) process of Juniper Networks Junos OS allows an adjacently-connected attacker to cause a Denial of Service (DoS) by sending a crafted ARP packet to the device. Continued receipt and processing of the crafted ARP packets will create a sustained Denial of Service (DoS) condition. This issue affects: Juniper Networks Junos OS on EX2200-C Series, EX3200 Series, EX3300 Series, EX4200 Series, EX4500 Series, EX4550 Series, EX6210 Series, EX8208 Series, EX8216 Series. 12.3 versions prior to 12.3R12-S17; 15.1 versions prior to 15.1R7-S8. This issue only affects the listed Marvell-chipset based EX Series devices. No other products or platforms are affected.
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Analysis
by VulDB Data Team • 04/27/2021
The vulnerability identified as CVE-2021-0271 represents a critical double free condition within the software forwarding interface daemon sfid process of Juniper Networks Junos OS operating on specific EX Series devices. This flaw manifests as a denial of service vulnerability that can be exploited by attackers positioned within the same network segment. The vulnerability specifically targets Marvell-chipset based EX Series hardware platforms including EX2200-C, EX3200, EX3300, EX4200, EX4500, EX4550, EX6210, EX8208, and EX8216 series devices. The attack vector involves sending specially crafted ARP packets to the affected device, which triggers the double free memory error during packet processing. This particular vulnerability falls under CWE-415 which specifically addresses double free conditions in memory management, a well-documented class of vulnerabilities that can lead to system instability and service disruption. The impact extends beyond simple service interruption as the sustained processing of these crafted packets creates a persistent denial of service condition that can severely impact network operations and availability.
The technical implementation of this vulnerability occurs within the sfid daemon process responsible for handling software forwarding interface operations in Juniper's networking infrastructure. When the daemon receives and processes the malformed ARP packets, it executes flawed memory management routines that result in attempting to free the same memory block twice. This double free condition corrupts the heap memory structures and can potentially lead to arbitrary code execution or complete system crash depending on memory layout and timing conditions. The vulnerability is particularly concerning because it requires minimal network proximity for exploitation, making it accessible to adjacent network attackers who do not need to be directly connected to the device but can leverage network access to send malicious packets. The affected Junos OS versions include all 12.3 releases prior to 12.3R12-S17 and 15.1 releases prior to 15.1R7-S8, indicating a significant timeframe of vulnerable software versions that organizations may still be running in production environments. This vulnerability aligns with ATT&CK technique T1499.004 which covers network denial of service attacks targeting network infrastructure devices.
The operational impact of CVE-2021-0271 extends far beyond simple service disruption as it affects core network infrastructure components that typically operate with high availability requirements. Network administrators may experience complete loss of forwarding capabilities on affected devices, potentially leading to network segmentation and service interruption across multiple network segments. The sustained nature of the denial of service means that once an attacker successfully triggers the vulnerability, the device will remain in a disrupted state until manually rebooted or until the specific memory corruption is resolved through system restart. Organizations running these affected EX Series devices face significant risk of operational downtime, especially in mission-critical environments where network availability is paramount. The vulnerability's exploitation does not require authentication or complex attack chains, making it particularly dangerous as it can be leveraged by any adjacent network entity with basic network access. This characteristic places the vulnerability in the category of low-effort, high-impact attacks that can severely compromise network reliability and availability. The targeted hardware platforms represent critical edge and campus network infrastructure components that form the backbone of many enterprise and service provider networks, amplifying the potential business impact of exploitation. Organizations should prioritize immediate patching or mitigation strategies to address this vulnerability across their Juniper network infrastructure deployments.