CVE-2021-0254 describes a critical buffer size validation vulnerability in the overlayd service of Juniper Networks Junos OS. This vulnerability allows an unauthenticated remote attacker to send specially crafted packets to the device, potentially triggering a partial Denial of Service (DoS) condition or leading to remote code execution (RCE). Given that the overlayd daemon processes Overlay OAM packets, such as ping and traceroute, the service runs as root by default and listens on UDP port 4789. The vulnerability stems from improper buffer size validation, which may lead to a buffer overflow.
As a result of this flaw, continued receipt and processing of specially crafted packets can sustain the partial DoS condition. The overlayd service operates on various Juniper platforms, including the MX Series, ACX Series, and QFX Series. However, the SRX Series does not support VXLAN and is exempt from this vulnerability. Other platforms become vulnerable if a Virtual Extensible LAN (VXLAN) overlay network is configured.
This vulnerability has been assigned a CVSS score of 9.8, indicating its critical nature. Organizations utilizing vulnerable versions of Junos OS should prioritize remediation efforts, as the implications of this vulnerability can result in significant disruptions and security breaches.
Organizations are urged to take immediate action due to the critical severity of this vulnerability. Patching is essential to mitigate the risk of exploitation. Refer to vendor advisories for the latest updates and patches.
Vulnerability Details
The vulnerability allows attackers to exploit buffer size validation errors, potentially leading to unauthorized access and control over affected systems. The CVSS score of 9.8 categorizes this vulnerability as critical, emphasizing the need for urgent attention.
Technical Analysis
The root cause of this vulnerability lies in improper buffer size validation during packet processing. The attack vector is network-based, with low attack complexity and no privileges required for exploitation. Importantly, no user interaction is necessary. The impacts on confidentiality, integrity, and availability are all classified as high, making this a severe risk for organizations.
Risk & Impact Analysis
Risk to organizations includes potential unauthorized access and control over network infrastructure, which can result in data breaches and service interruptions. The blast radius is significant, given that the vulnerability affects multiple Juniper platforms, posing a widespread threat. Organizations should prioritize patching immediately to safeguard their systems.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
This vulnerability affects all versions of Juniper Networks Junos OS prior to the specified patches: 15.1 versions before 15.1R7-S9; 17.3 before 17.3R3-S11; 17.4 before 17.4R2-S13 and 17.4R3-S4; 18.1 before 18.1R3-S12; 18.2 before 18.2R2-S8 and 18.2R3-S7; 18.3 before 18.3R3-S4; 18.4 before 18.4R1-S8, 18.4R2-S7, and 18.4R3-S7; 19.1 before 19.1R2-S2 and 19.1R3-S4; 19.2 before 19.2R1-S6 and 19.2R3-S2; 19.3 before 19.3R3-S1; 19.4 before 19.4R2-S4 and 19.4R3-S1; 20.1 before 20.1R2-S1 and 20.1R3; 20.2 before 20.2R2, 20.2R2-S1, and 20.2R3; 20.3 before 20.3R1-S1.
Mitigation & Remediation
Organizations should prioritize patching immediately. Specific updates for affected versions can be found on the Juniper Networks support site. For those unable to apply patches, consider implementing network segmentation and monitoring to reduce exposure.
Detection Guidance
Monitor logs for unusual traffic patterns, particularly on UDP port 4789. Behavioral anomalies may include unexpected packet sizes or rates. Establish network signatures to detect exploitation attempts.
AppSecure Threat Intelligence Insight
This vulnerability highlights the importance of robust input validation in network services. As adversaries become more adept, vulnerabilities such as these can lead to significant operational disruptions. Organizations should consider conducting thorough application security assessments to identify similar weaknesses and improve their security posture.
For more information on application security, refer to our resources on application security assessments and penetration testing to fortify defenses against future threats.
Organizations should also stay informed about emerging threats and vulnerabilities by following our blog on emerging vulnerabilities and penetration testing methodologies to enhance their security strategies.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
.webp)