CVE-2021-27365 is a high-severity vulnerability affecting the Linux kernel through version 5.11.3. This vulnerability allows an unprivileged user to send a Netlink message associated with iSCSI data structures, which do not enforce appropriate length constraints. Consequently, these structures can exceed the PAGE_SIZE value, leading to potential security breaches.
With a CVSS score of 7.8, this vulnerability poses significant risks to organizations. The attack vector is local, which necessitates that an attacker must have local access to the system to exploit this vulnerability. The low attack complexity and required privileges further enhance the likelihood of exploitation.
Risk to organizations includes unauthorized access and potential data corruption. As such, organizations must act swiftly, as the exploitation status is confirmed with a known exploit available in the wild. Organizations should prioritize patching immediately.
Given the nature of this vulnerability and the potential impact, it is crucial for organizations running affected systems to implement the necessary patches as soon as possible.
Vulnerability Details
The official CVE description states that an issue was discovered in the Linux kernel through version 5.11.3. Certain iSCSI data structures do not have appropriate length constraints or checks, allowing them to exceed the PAGE_SIZE value. An unprivileged user can send a Netlink message associated with iSCSI, having a length up to the maximum length of a Netlink message.
The vulnerability falls under the CWE classification, specifically CWE-787, which deals with improper access control. This highlights a significant oversight in the kernel's management of iSCSI data structures.
The CVSS score for this vulnerability is 7.8, categorized as high severity. The attack vector is local, with low complexity, requiring low privileges and no user interaction. It significantly impacts confidentiality, integrity, and availability.
Technical Analysis
The root cause of CVE-2021-27365 stems from inadequate length checks on certain iSCSI data structures in the Linux kernel. This oversight allows a local user to manipulate Netlink messages, potentially leading to memory corruption or other unintended behavior.
Since the attack vector is local, an attacker must have access to the system. The attack complexity is low, meaning an unprivileged user could easily exploit this vulnerability without special skills. No user interaction is required, making it easier for attackers to execute their plans.
The implications of this vulnerability are severe, affecting confidentiality, integrity, and availability. Attackers could potentially manipulate system behavior, leading to data exposure or corruption.
Risk & Impact Analysis
Real-world deployment risk is high due to the local nature of the attack vector and the low complexity involved in exploitation. Organizations relying on affected Linux kernel versions may find themselves vulnerable to unauthorized access and potential data corruption.
The blast radius includes any system that utilizes the affected kernel versions, potentially impacting critical infrastructure and sensitive data.
Organizations should assess their exposure and prioritize patching, particularly given the high CVSS score and confirmed exploit availability. The urgency for patching cannot be overstated.
Signal | Status |
|---|---|
Known Exploit | Yes |
Public PoC | Yes |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The following versions are affected by this vulnerability:
Linux kernel versions up to 5.11.3 are vulnerable. Additionally, systems running Debian Linux 9.0 and specific versions of Oracle Tekelec Platform Distribution and NetApp Solidfire Baseboard Management Controller Firmware are also at risk.
Mitigation & Remediation
To mitigate CVE-2021-27365, organizations should apply the latest patches provided by their Linux distributions. For Debian users, patches have been released that address this vulnerability. Organizations should regularly check and apply updates to ensure systems are protected against known vulnerabilities.
Further, implementing strong network controls and monitoring systems for unusual activity can help detect potential exploitation attempts. For comprehensive security, organizations should consider penetration testing to identify and remediate similar weaknesses.
Detection Guidance
Organizations should monitor logs for indicators of exploitation, including unexpected Netlink messages and abnormal system behavior. Behavioral anomalies, such as unauthorized changes to system configurations or unexpected crashes, should also be closely examined.
Having a strategy for timely detection can minimize the impact of such vulnerabilities.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2021-27365 lies in its demonstration of how unprivileged access can lead to severe vulnerabilities in widely used systems. It highlights the importance of rigorous validation in system design to prevent similar issues.
This vulnerability represents a trend toward increased scrutiny of kernel-level security, which is critical for maintaining system integrity.
Security teams should learn from this incident by prioritizing comprehensive security assessments and implementing proactive measures that include regular penetration testing methodologies to identify vulnerabilities before they can be exploited.
Organizations can also benefit from engaging in regular security training for their teams to enhance awareness and preparedness against such vulnerabilities.
To further enhance their security posture, organizations may consider adopting a vulnerability management program that regularly evaluates and addresses security weaknesses.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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